new salt chlorinator system [Archive]

waterbear

04-29-2012, 11:16 AM

pH control is moer than just adding acid or lowering TA. The main cause of pH rise with salt systems (excluding such factors as new, curing plaster) is outgassing of CO2. The outgassing is minimized by a multifaceted approach:

1. Keep CYA at the manufacturers MAXIMUM (usually 80-100 ppm) and run the FC at 5% of the CYA level. This translates into a shorter cell on time, which translates into less generation of hydrogen bubbles in the cell, which tranlsates into less aeration of the water, which translates into less outgassing of CO2, which translates into slower pH rise.

2. Lower the TA to around 70 ppm (or even a bit lower). If the pool is plaster (or fiberglass since there is some emperical evidence that higher calcium might help lower the tendency toward staining) then raise the CH to maintain the calcium saturation index. Lower TA means less bicarbonate in the water. Less bicarbonate means less outgassing of CO2 which means slower pH rise,

3, Do not let the pH go above 7.8. When it does do not lower it below 7.6. (This is actually easier to do than it sounds with a bit of trial and error on how much acid to put in or you can use an acid demand test to get an idea of how much acid you need. ) The lower you put the pH the faster it will rise because you convert more bicarbonate in carbonic acid (essentially CO2 dissolved in the water) which then outgasses.

4. Add 50 ppm borate (easy to do with borax and acid) to provide a secondary pH buffer that work with the bicarbonate buffer we call TA and effectively keeps the pH at 7.7 to 7.8 for a longer period of time then without the borate.

When these 4 steps are done together pH rise and scale buildup in a salt system can be minimized.

JimK

05-19-2012, 12:31 PM

......
1. Keep CYA at the manufacturers MAXIMUM (usually 80-100 ppm) and run the FC at 5% of the CYA level. This translates into a shorter cell on time, which translates into less generation of hydrogen bubbles in the cell, which tranlsates into less aeration of the water, which translates into less outgassing of CO2, which translates into slower pH rise.

.....

My appologies to the OP for being off topic, but his item caught my attention.

My SWG (Aquarite) recommends a CYA level of 60-80 (80 being ideal). So keeping CYA at 80, 5% of that results in a recommended FC level of 4. This is lower than recommended on the "Best Guess" chart (Best Guess chart says min FC of 5 at this CYA level).

Could you clarify this for me? If I can keep FC at 4, this will save some wear on my salt cell (which is a good thing considering the cost of replacement cells!).

Thanks.

PoolDoc

05-19-2012, 12:53 PM

My SWG (Aquarite) recommends a CYA level of 60-80 (80 being ideal). So keeping CYA at 80, 5% of that results in a recommended FC level of 4. This is lower than recommended on the "Best Guess" chart (Best Guess chart says min FC of 5 at this CYA level).

Could you clarify this for me? If I can keep FC at 4, this will save some wear on my salt cell (which is a good thing considering the cost of replacement cells!

Sorry, I had a response here that was a result of not fully reading what you wrote -- the rule about ASSUMING was in full force. But, let me try again.

There are two sets of recommendations -- besides my own Best Guess -- that I need to address here.

First, the SWCG manufacturers have lined up behind the old industry standard recommendations, which they've tweaked a bit, to raise the CYA level, but otherwise left unchanged. For example, Hayward's Aqua Rite manual (http://www.hayward-pool.com/pdf/manuals/Manual239.pdf) suggests an ideal CYA level of 80 ppm, and a FC level between 1 - 3 ppm. It was this set of recommendations that I thought (because I hadn't fully read your post) you were asking about. And it's nonsense. If you follow it, and fail to use a supplemental algaecide, you will have problems.

They (the pool industry generally) are wrong; we (BBB method folk) are right. And, more specifically, the SWCG makers are borrowing a BUNCH of trouble for themselves, in the form of dissatisfied customers by following these dumb recommendations.

But, there's another issue.

TroubleFreePool.com -- I think; I'm not quite sure where it came from -- has promoted a percentage based adjustment of FC levels, including the 5% rule. The idea of a simple percentage based rule is a good one, IF it works. The problem is, it doesn't. I'm not sure why: it may be that the range needs to be higher. Or, it may be something else.

But, just to take a real world example: I have been servicinga pool, that has CYA = 100 - 120 ppm, and was being cleaned up from some algae on the walls, and in some leaf piles that had resulted from holes in the mesh cover. The water was crystal clear. To kill the algae, I'd raised chlorine levels to 30+ ppm (30%), and it was mostly dead. However,chlorine levels had dropped from 15 - 20 ppm 3 days ago, to 10 ppm yesterday morning. And, mustard algae had begun growing rapidly!

Now, let's summarize:

+ Intial state: pH 6.8 - 7.0; FC 5.0; heavy algae on walls and under leaf piles
+ 3 - 5 days ago: pH 6.6 - 6.8; FC: 40 ppm descending to 20 ppm; algae dead on walls and dying in leaf piles
+ 2 days ago, AM: pH 6.6 - 6.8; FC 10 ppm -- RAPID (overnight) mustard algae growth
+ 2 days ago, PM; pH 7.4 - 7.6; FC 40 ppm -- slow mustard algae death
+ 1 day ago: pH 7.4; FC 25 ppm -- continued slow mustard algae death
+ This AM: pH 7.4; FC 25 ppm -- continued slow mustard algae death

Looking at it through the percentage model: the pool accumulated HEAVY algae (non-planktonic) at FC = 5% of CYA or HIGHER; it cleared at at FC = 40% of CYA, but over days, not hours. It began to RE-GROW at FC = 10 - 15% of CYA.

Richard (Chem_Geek) has done me, the PoolForum, TFP, and pool owners as a whole, a HUGE service by combining the work of a number of lab chemists, into an analytical model that can be applied to pools. That's a GREAT thing, and one I value highly.

But, I'm much less enthusiastic about the assumption that many seem to make (I'm not sure Richard does this) that this analytical understanding of the CYA / Chlorine relationship FULLY explains what's going on in pool chemistry. The CYA/Cl relationship is a PIECE of the puzzle, but it's FAR from the whole puzzle. I could run this post on for pages, listing un-answered questions I have about pool chemistry. And, I am 100% sure that that list would omit many important questions . . . because I don't know to ask them.

So, while I'm fully convinced that Richard knows more about the analytical aspects of swimming pool chemistry than anyone else in the world, that does NOT mean I believe Richard yet possesses (or is likely to possess in my lifetime) a full and complete analytical model for the chemistry and microbiology of swimming pool. And, until we have a full analytical model for swimming pools, we have to use an empirical model, that combines what we can learn from the (partial) analytical models, with what we can observe.

MY observation is that my Best Guess values are more likely to 'work' most of the time, than the 5% rule is.

That doesn't mean the 5% rule won't work for you! Precisely because we do NOT have a full analytical model, we often see things happening in pools, that we do not understand. A perfect analytical model would always predict what would happen in YOUR pool. The fact that we (BBB proponents) have a BETTER model than the pool industry as a whole does NOT mean we have a perfect model, or even a good approximation of a perfect model.

So, we have to fall back on real world observation. Our recommendations are just that: recommendations.

But the 'acid test' is, does it work?

If 5% works for you, GREAT! But, it's not what I recommend.

JimK

05-19-2012, 05:50 PM

Thanks Ben.

After re-reading my post, I guess I should have specified that I don't follow the SWCG manufacturer's recommendation on FC levels (1-3) since in the past it has just resulted in algae problems; not visible algae, but a slick liner, which I imagine would have turned into visible algae had I not addressed it quickly. Even with FC levels at 7-8, I was still having problems (important to note that at that time I was not using borates or Polyquat 60).

Your explanation seems to mirror one thing I've learned since having a pool (this is the only pool I've ever owned; installed in 2004), that what works for one pool may not work for another. I suspect that at least part of the reason is that the environment around the pool is likely different for every pool.

Thanks to sites like this and a particular pool store manager that was genuinely interested in helping me and not just selling me a bunch of chemicals, I've learned quite a bit over the years and continue to do so.

After a steep learning curve, I settled on a routine that has worked for me for the past several seasons. It pretty much includes the following:

FC at 5 (as mentioned, controlled using an Aquarite SWCG)
TA 80-100 (I use bicarb to raise when it gets low)
PH 7.5-7.8 (I add muriatic acid once it hits 7.8; PH has never been too low, so I've never had to add anything to raise it)
Borates 40-50
CYA 70-80

In terms of regular maintenance, besides testing and adjusting the above as needed, each week I add a maintenance dose (8oz) of Polyquat 60 and a maintenance dose of Jack's Magic Purple Stuff (12oz; I use to have problems with staining before using this. I was told the staining was a side effect of the SWCG. Since using it, I've not had any staining problems.). I shock every 2 weeks (or after a big storm) using calcium hypochlorite (68%). Also, I run the automatic vacuum frequently to keep the pool clean (every couple days on average).

I'm not sure if I'm overdoing things and wasting money by using both Poly60 and borates. I started using them at about the same time (I was fed up with the liner frequently getting slick with aglae so decided to hit it with both guns!) so I'm not sure if just using one would give me the same algae control.

I would appreciate your input on my routine and if you have any suggestions that may save me time and money.

Thanks again.

JimK

05-19-2012, 08:26 PM

(testing addition of signature)

Watermom

05-19-2012, 08:31 PM

It's there!

PoolDoc

05-19-2012, 09:37 PM

I would appreciate your input on my routine and if you have any suggestions that may save me time and money.

Jim, I had to go look up some of your IP addresses, to find out approximately where you are. Virginia is much more like Tennessee or N. Georgia, then like California . . . and I'm pretty sure we have more of a problem with algae than folks in S. California or Arizona.

Richard (Chem_Geek), Mark (mas985) and I have gotten an email discussion going about this that's probably up to 3,000 words in just a few hours. I guess we'll need to migrate it to the China Shop.

In your case, if I were you, I'd experiment with dropping the polyquat rather than the borates. Unless you are backwashing a LOT, you shouldn't be having to add borates much. One caution: polyquat is a pretty effective clarifier, so if that function is affecting your pool and you lose clarity you might try substituting a small dose of a conventional clarifier.

You might want to raise the borate level a bit. I still have no hard data, but it seems that 50 ppm may be the low end of the range for effective algae-stasis.

Best wishes!

waterbear

05-19-2012, 09:43 PM

waterbear

05-19-2012, 09:53 PM

After a steep learning curve, I settled on a routine that has worked for me for the past several seasons. It pretty much includes the following:

FC at 5 (as mentioned, controlled using an Aquarite SWCG)
TA 80-100 (I use bicarb to raise when it gets low)

If you drop the TA down to 70 or even 60 you will have a slower pH rise since there will be less outgassing of CO2, the primary cause of pH rise in most pools (excluding curing plaster).

PH 7.5-7.8 (I add muriatic acid once it hits 7.8; PH has never been too low, so I've never had to add anything to raise it)

Wait for the pH to climb above 7.8. If you are testing it regularly you will see when this happens before it goes too high. Borate tends to stabilize the pH at 7.7 to 7.8 for an extended period of time compared to pools without borate.

Borates 40-50
CYA 70-80

In terms of regular maintenance, besides testing and adjusting the above as needed, each week I add a maintenance dose (8oz) of Polyquat 60 and a maintenance dose of Jack's Magic Purple Stuff (12oz; I use to have problems with staining before using this. I was told the staining was a side effect of the SWCG. Since using it, I've not had any staining problems.). I shock every 2 weeks (or after a big storm) using calcium hypochlorite (68%). Also, I run the automatic vacuum frequently to keep the pool clean (every couple days on average).

I'm not sure if I'm overdoing things and wasting money by using both Poly60 and borates. I started using them at about the same time (I was fed up with the liner frequently getting slick with aglae so decided to hit it with both guns!) so I'm not sure if just using one would give me the same algae control.

I would appreciate your input on my routine and if you have any suggestions that may save me time and money.

Thanks again.
I would use sodium hypochlorite (liquid chlorine or bleach) instead of the cal hypo. I assume you are not testing your CH because it is a vinyl pool. This is NOT a good idea with a SWCG since scaling of the cell is a real worry. Just because you don't NEED calcium added if it is low does not mean you do not need to know what the level is so you can avoid possibly scaling conditions.

PoolDoc

05-19-2012, 09:57 PM

Just because you don't NEED calcium added if it is low does not mean you do not need to know what the level is so you can avoid possibly scaling conditions.

Good reminder!

JimK

05-20-2012, 12:03 AM

Jim, I had to go look up some of your IP addresses, to find out approximately where you are. Virginia is much more like Tennessee or N. Georgia, then like California . . . and I'm pretty sure we have more of a problem with algae than folks in S. California or Arizona.

Yes, I'm on the coast, lots of water around here and lots of humidity during the summer!

In your case, if I were you, I'd experiment with dropping the polyquat rather than the borates. Unless you are backwashing a LOT, you shouldn't be having to add borates much. One caution: polyquat is a pretty effective clarifier, so if that function is affecting your pool and you lose clarity you might try substituting a small dose of a conventional clarifier.

Once up and running, I usually only have to backwash my DE filter once or twice the entire season (May-October). The water has always stayed crystal clear, even before I started using the polyquat, so perhaps losing clarity may not be an issue? It's not very often I have to add borates. I may try stopping the polyquat applications and see what happens. That said, I've already purchased enough polyquat to last the entire season, so I may just continue with it this season and try doing without next season (unless curiosity gets the best of me and I don't want to wait that long...LOL).

You might want to raise the borate level a bit. I still have no hard data, but it seems that 50 ppm may be the low end of the range for effective algae-stasis.

Best wishes!

Can you recommend a more effective range? BTW, if it makes a difference, the borate I'm using is BioGuard's "Optimizer" (I'm sure it cost more per pound, but a 20lb bucket lasts me a long time, so my cost per season is low). The label on the bucket recommends keeping the level at least 35, I shoot for 50 because this was recommended by someone I trust. If you need it, I can check the container tomorrow and see what the chemical name is for "Optimizer" (it's a big long name that I don't remember).

I would use sodium hypochlorite (liquid chlorine or bleach) instead of the cal hypo. I assume you are not testing your CH because it is a vinyl pool. This is NOT a good idea with a SWCG since scaling of the cell is a real worry. Just because you don't NEED calcium added if it is low does not mean you do not need to know what the level is so you can avoid possibly scaling conditions.

Thanks for the tips on TA levels and PH.

Actually, I do have CH checked a couple times a year. I just checked my records going a couple years back and the level seems to always be in the 200-250 range. I've never experienced scaling on the salt cell. Perhaps we get enough rain here in SE VA to keep CH levels in check? Speaking of CH levels, the paperwork that came with my pool states that CH is necessary to keep the liner from becoming brittle. Is this true or BS?

After reading the posts and recommendations in this forum, I've considered using plain bleach, but with all the uncertainties about it's actual strength (how long has that jug been sitting on the shelf or in a warehouse?), keeping a bunch of jugs on hand or making frequent trips to the store (I don't like shopping), using cal hypo just seems much more convenient to use (I just have to buy it once at the beginning of the season). Since my CH level seems to stay in check, do you think it's OK to keep using cal hypo?

PS - I forgot to mention when describing my routine that I try to always test my water at about the same time in the evening (about 6pm). I figure this would give me a FC reading at its lowest point during the day. I take the sample from the deep end about 18" below the surface and away from any returns.

JimK

05-20-2012, 12:22 AM

Ben, the 5% CAME from Chem geek! It has been proven to be effective in a vast majority of salt pools, possibly because of the super shocking that occurs in the cell. (In fact I am not familiar with one case where there were algae problems with someone following it and making sure that FC did not drop below that but,as we know, there are always exceptions to everything!) Also, remember that 5% is the MINIMUM FC level you should run.

Interesting that this pool calculator, www.poolcalculator.com/ , recommends the same thing. If I type in a CYA level of 80, for SWCGs it recommends a minimum FC level of 4 (ie 5%).

Here's a snippet from that site;

...Many people find that a SWG will work with a slightly lower FC level than other forms of chlorine....

waterbear

05-20-2012, 01:37 AM

PoolDoc

05-20-2012, 07:20 AM

Speaking of CH levels, the paperwork that came with my pool states that CH is necessary to keep the liner from becoming brittle. Is this true or BS?

I've several times talked to engineers at the companies that make the vinyl sheeting (not completed liners) and they tell me it is NOT true. In any case, if you did have loss of calcium chloride, it wouldn't make the vinyl brittle. PVC is naturally brittle, with or without calcium carbonate filler -- you have to add a plasticizer to make it flexible. Loss of plasticizer WILL make it brittle.

Interesting that this pool calculator, www.poolcalculator.com/ , recommends the same thing. If I type in a CYA level of 80, for SWCGs it recommends a minimum FC level of 4 (ie 5%).

As Waterbear notes, it's not exactly a coincidence.

50 to 80 ppm is recommended for biguanide pools but there is a very small concern of possible toxicity at the higher levels.

As best I can tell, the toxicity issue applies primarily to folks who have (a) male dogs who (b) drink a lot of pool water, and (c) have not been fixed, but are planned (d) for breeding. Significant borate ingestion can impair canine fertility and is possibly mutagenic. One of the other PF Support Team members does not use borates because she breeds German Shepherds and they do drink a lot of pool water.

JimK

05-20-2012, 12:13 PM

The pool calculator was originally written by "JasonLion" over at TFP and it was at TFP where chem geek (Richard) basically came up with the 5% and we tested it out and it worked very well (back when I was a Mod over there) so it's no surprise that Jason incorporated Richard's guidelines into his pool calculator. We did a lot of experimentation and 'tweaking' in the early days of TFP. The pool calculator has since been sold to pSIFlow Technology Inc. and I am not sure if it is being updated anymore.

Thanks for the clarification.

The active ingredient in the original Optimizer is/was sodium tetraborate pentahydrate (borax). It requred the addition of acid along with it to maintain the pH.

Yes, this is what I use. I have to add acid as it does cause the PH to shoot up.

...50 ppm is considered optimum for borate in a halogen (chlorine or bromine) pool, 30 ppm is the lowest effective level for algaestatic effect. 50 to 80 ppm is recommended for biguanide pools but there is a very small concern of possible toxicity at the higher levels. These levels go back to the original tests done by John Girvan of Proteam in his test pools in St. Augustine and Jacksonville, Florida in the early '80s before he sold his company to Haviland and went to work for them...

So according to this information, my borate level of 50 is fine. Correct?

I've several times talked to engineers at the companies that make the vinyl sheeting (not completed liners) and they tell me it is NOT true. In any case, if you did have loss of calcium chloride, it wouldn't make the vinyl brittle. PVC is naturally brittle, with or without calcium carbonate filler -- you have to add a plasticizer to make it flexible. Loss of plasticizer WILL make it brittle.

I see. It has been quite some time since I purposely added calcium to the pool since the CH level always seems to be in the lower to mid 200s (last night I checked my records going back a few seasons to verify this). As was mentioned here, I guess the calcium is coming from the cal hypo I use to shock, and since it hasn't been continually increasing, I'm assuming that we get enough water exchanges via rain throughout the season to keep it in check. Also, I've never experienced any scaling on the SWCG cell.

You said the loss of plasticizer would cause the vinyl to become brittle. What causes a loss of plasticizer?

As best I can tell, the toxicity issue applies primarily to folks who have (a) male dogs who (b) drink a lot of pool water, and (c) have not been fixed, but are planned (d) for breeding. Significant borate ingestion can impair canine fertility and is possibly mutagenic. One of the other PF Support Team members does not use borates because she breeds German Shepherds and they do drink a lot of pool water.

That's not an issue here as we don't have any dogs. Besides, if we did have any, they would be fixed (I use to work at an animal shelter know all too well the consequences of too many dogs and cats and not enough good homes; it's absolutely heartbreaking......).

You mentioned you thought a borate level of 50 might not be enough. Could you elaborate and suggest a level that may be more appropriate for me?

Thanks everyone. I'm learning alot here and appreciate the feedback.

I do feel bad for hijacking this thread, so I'll at least try to share with the OP some of my experience with using a SWCG.

First of all, although this is the only pool I've ever owned and it has always had a SWCG so I cannot compare 1st hand to a traditionally chlorinated pool, my guess is that despite what manufacturers say there is really no cost savings in the long run (the units aren't cheap and replacement cells are expensive). I think in the end overall costs are similar.

Also, even though my SWCG has a "superchlorinate" feature (causes it to run at 100%) for shocking, I no longer use it. With my first/original cell, I did use this feature on a regular basis (per pool stores instructions) and my cell ended up failing within 4 years (it still had a little warranty left on it, so the replacement cost was reduced). I stopped using the superchlorinate feature once I got the new cell. It makes sense to me that the fewer hours I put on the cell, the longer it will last. So now when I want to shock, I turn the cell off and just use the traditional method (cal hypo in my case). Next month it will have been 4 years since I got the replacement cell and so far it's still working fine. Hopefully this means I will get more seasons out of this cell than the last one. Bottom line, I only use the SWCG to maintain FC levels.

The first few years of owning my pool, I had an issue with metal staining (each successive season it got worse and more frequent). At first it was just on the steps and I had to clean them a couple times a season with ascorbic acid (not a big deal). As time/seasons went by, the steps would stain more frequently and eventually the entire liner started showing staining (a big dose of ascorbic acid was required to get rid of all the stains: the process was a pain but it worked). The manager of the place who installed our pool said that this was a side effect of the SWCG; that the small amount of impurities (iron?) in the pool salt were building up and causing the staining. At that time after a bit a research I started using Jack's Magic Purple Stuff and have not experienced any staining since (a tip: ordering it online is much cheaper than buying it in the store, although it still cost me about $200 per season [May-October here]). Supposedly, it's also suppose to help protect the cell and help it last longer. I would like to hear from our experts here about this issue with SWCGs (if it really is the cause).

In another thread in which I was asking if CYA was necessary, I referenced an article I found that included that person's experience using a SWCG. He complained that the cell failed within a year and the manufacturer wouldn't honor the warranty. I found this puzzling since I've also experienced a couple problems while under warranty and had no trouble with the same manufacturer honoring it. It made me wonder if the reason his warranty claim was denied is because he didn't maintain the pool according to the manufacturer's instructions (he wasn't using any CYA). He also complained that the salt was corroding his stainless ladder. I also found this puzzling since I've never experienced this issue (our pool was installed in 2004 and has always used a SWCG since day one). I guess just make sure you don't keep too much salt in the pool (follow the manufacturer's guidelines).

For me, there are three primary advantages to having a SWCG;

1. Convenience. Maintaining constant FC levels is easy once you get everything balanced and going. I don't have to mess with handling and storing chlorine (except for the cal hypo I use to shock with).

2. The water feels better and is much less irritating to my skin and eyes (friends have also mentioned this about our pool). That said, perhaps you could get the same benefit in a traditionally chlorinated pool by adding salt to it (what do our experts here think?)?

3. We can go on vacation without worrying about maintaining FC levels.

I hope something in here helps the OP.

waterbear

05-20-2012, 02:00 PM

A few thoughts:
50 ppm borate is fine in my opinion.

A cheaper source of borax is 20 mule team borax from the grocery. It's the same stuff except that it is the decahydraate form (it has 10 water molecules attached instead of 5) so you need a bit more by weight for the same borate level (60 oz by weight will raise 1000 gallons 50 ppm and needs abut 30 fluid oz of muriatic acid to keep the pH in line. The pentahydrate form requires about 45 oz by weight and the amount of acid to achieve 50 ppm rise in borate in 1000 gallons while using boric acid requres about 38 oz by wieght and will very slightly lower the pH but this is not a concern since it will rise on it's own as CO2 outgasses.)

If you want a pH neutral borate souce that is available commercially then Proteam Supreme Plus is the product you want. Proteam Supreme is exactly the same at Bioguard Optimzer (sodium tetraborate pentahydrate). The Supreme Plus is a mix of boric and and the pentahydrate form of borax to make it pH neutral. However, all the commercial forms of borax are MUCH more expensive than 20 mule team borax from the grocery store.

The main reason to use sodium hypochlorite (particularly since you have a vinyl liner) is that calcium hypochlorite is slow dissolving and can bleach the liner if it falls on it undissolved. Also, Sodium hypochlorite is what the salt cell is is actually making. As far as worrying about the 'freshness of the bleach" it's really a moot point. Unless you are buying it at a discount store or dollar store it's probably fresh. Walmart has a big turnover so it's a good place to buy it. If they sell pool chlorine in refillable carboys in your area that is often the best deal. Just buy enough for shocking and don't stockpile it so it does not stick around for more than a month or two before getting refilled. One gallon of 12.5% pool chlorine will raise you pool about 6 ppm, btw, so a 2 1/2 gallon carboy should be just about right for shocking your 22000 gal pool (or 5 gallons of 6% laundry bleach). If you use cal hypo predissolve it first. You do not want undissolved cal hypo going through the salt cell or falling on your liner.

As far as your metal problem, Were the stains brown (iron)? Do you fill with well water? What kind of salt do you use? I have seen some fine crystal "pool salts" that have caused iron staining which is why I recommend using solar water softener salt (The larger crystals do not need anti caking agents). I suspect that anti caking agents are sometimes added to the fine crystal pool salt or they are using food salt (which also contains anti caking agents) and repackaging it. Yellow prussiate of soda (sodium ferrocynaide, an iron salt) is used as an anti caking agent in food salt.

JimK

05-20-2012, 09:13 PM

A few thoughts:
50 ppm borate is fine in my opinion.

Thanks.

A cheaper source of borax is 20 mule team borax from the grocery. It's the same stuff except that it is the decahydraate form (it has 10 water molecules attached instead of 5) so you need a bit more by weight for the same borate level (60 oz by weight will raise 1000 gallons 50 ppm and needs abut 30 fluid oz of muriatic acid to keep the pH in line. The pentahydrate form requires about 45 oz by weight and the amount of acid to achieve 50 ppm rise in borate in 1000 gallons while using boric acid requres about 38 oz by wieght and will very slightly lower the pH but this is not a concern since it will rise on it's own as CO2 outgasses.)

If you want a pH neutral borate souce that is available commercially then Proteam Supreme Plus is the product you want. Proteam Supreme is exactly the same at Bioguard Optimzer (sodium tetraborate pentahydrate). The Supreme Plus is a mix of boric and and the pentahydrate form of borax to make it pH neutral. However, all the commercial forms of borax are MUCH more expensive than 20 mule team borax from the grocery store.

Great information. Regarding cost, the last time I bought BioGuard Optimizer, spring 2011, I paid about $40 for a 20# bucket, so about $2/lb. A quick check online showed 20 Mule Team Borax close to that, about $1.70/lb. So I really didn't pay much more, perhaps about even or less when you consider you don't need as much to achieve the same borate level. That said, I just did a quick online check for Optimizer and found a 20# bucket running about $60. Not sure why I got it so much cheaper at a local pool store last year. Out of curiosity I'll call them tomorrow and see what they currently charge. If it has gone up alot, then I'll switch to borax. I also did an online check for boric acid and it was very expensive, so that option is out (it would be nice not to have to add so much acid). Proteam Supreme Plus also looks to be very expensive.

The main reason to use sodium hypochlorite (particularly since you have a vinyl liner) is that calcium hypochlorite is slow dissolving and can bleach the liner if it falls on it undissolved. Also, Sodium hypochlorite is what the salt cell is is actually making. As far as worrying about the 'freshness of the bleach" it's really a moot point. Unless you are buying it at a discount store or dollar store it's probably fresh. Walmart has a big turnover so it's a good place to buy it. If they sell pool chlorine in refillable carboys in your area that is often the best deal. Just buy enough for shocking and don't stockpile it so it does not stick around for more than a month or two before getting refilled. One gallon of 12.5% pool chlorine will raise you pool about 6 ppm, btw, so a 2 1/2 gallon carboy should be just about right for shocking your 22000 gal pool (or 5 gallons of 6% laundry bleach). If you use cal hypo predissolve it first. You do not want undissolved cal hypo going through the salt cell or falling on your liner.

Understood. I don't put dry cal hypo directly in the pool; I've always pre-dissolved it in a bucket then put it in the pool. Using this method I've not had any issues with the liner. I'll have to check local prices for bleach. Locally I pay $2/lb for 68% cal hypo. I buy it by the bucket, 40-50lbs, instead of by the 1lb bag which is much more expensive.

As far as your metal problem, Were the stains brown (iron)? Do you fill with well water? What kind of salt do you use? I have seen some fine crystal "pool salts" that have caused iron staining which is why I recommend using solar water softener salt (The larger crystals do not need anti caking agents). I suspect that anti caking agents are sometimes added to the fine crystal pool salt or they are using food salt (which also contains anti caking agents) and repackaging it. Yellow prussiate of soda (sodium ferrocynaide, an iron salt) is used as an anti caking agent in food salt.

Yes, the stains were brown and disappeared almost instantly when ascorbic acid was applied. We are on city water which comes from a reservoir, not wells. I use "pool salt" from the pool store. I was told it has no anti caking agents. There was nothing on the label to indicate either way, so perhaps it did have some kind of additive? During my first season with the pool, I tried using solar water softener salt (how pure is it?) but the large crystals took so long to dissolve it was very time consuming and a pain to add salt. I did notice that this year my pool store is selling a different brand of pool salt. The brand is Aqua Salt ( http://www.aquasalt.com/aquasalt/website.nsf/html/aquasalt_overview.htm ). I just took a look at the bag and just noticed it says "Enhanced with a natural stain fighter". Is this a bad thing? Or would using this salt eliminate the need for the Purple Stuff?

That brings up a question. Let's assume that the salt I've been using does have an additive that's introducing iron to the water and in turn is the cause of the stains. As I understand it, Jack's Magic Purple Stuff is a sequestering agent that keeps the metals in suspension. The manufacturer says it allows the filter to remove the metal, but I read that it merely keeps the metal from coming out of suspension and attaching to surfaces such as the steps and liner. Please correct me if I have this wrong. So if the metal is staying in the pool, is the only way I could get away from using the Purple Stuff is to do a complete water change and start over using solar salt, assuming it has no metals in it (do we know this?)?

If I could get to the point where I didn't need the polyquat and the Purple Stuff, that would save me about $400 a season (it cost about $200 for each per season). Up until now I've just accepted the extra expense because since adding them to my routine I've not had any algae problems or staining problems (note that I started using polyquat and borates about the same time, so I really can't say if the polyquat is making a significant difference).

Thanks again for the great feedback. This is very educational and helpful.

PoolDoc

05-20-2012, 09:54 PM

+ Borax is about $0.65 - 0.75/lb at Walmart.
+ A "natural" stain fighter could be a chitin (shrimp shell) product OR it could be a mined ortho-phosphate. Better not.
+ Purple Stuff is one of 3 Jack's products that are HEDP, a chlorine resistant phosphonate. These eventually break down to ortho-phosphates and release the chelated metals.
+ There are 3 possible strategies for removing metals:
=> CuLater zeolite-like patented product. Maker *claims* that it will remove phosphonate chelated metals. Available from Amazon:

1 ppm Culator, direct from Amazon (http://www.amazon.com/exec/obidos/ASIN/B003C5PNUW/poolbooks)
1.5 ppm Culator, sold by Amazon, shipped from Periodic (http://www.amazon.com/exec/obidos/ASIN/B004Y6RK3Q/poolbooks)
4 ppm Culator, sold by Amazon, shipped from Periodic (http://www.amazon.com/exec/obidos/ASIN/B007AHDMTM/poolbooks)

=> Flocculant use -- PAC (polyaluminum chloride) dosed slowly pre-filter should gradually remove metals.

GLB Pool & Spa Products 71408 1-Quart Drop n' Vac Pool Water Clarifier @ Amazon (http://www.amazon.com/exec/obidos/ASIN/B0002KT6TY/poolbooks)

=> Oxidation onto the filter with calcium hypochlorite.
(I've done this myself, repeatedly. But it's method dependent and if you are not careful, can result in stains.)

OK. Those are the options, but each as problems.

CuLator is zero risk and very easy; you can use it simultaneously with HEDP, and (reportedly) remove the metals while still protecting your pool with HEDP, because (reportedly, again) the CuLator material has a higher affinity for the metals than HEDP. But, it's unproven, and intrinsically slow, since you must pass all of the pool water over this little baggie sitting in your skimmer. You'd probably want to use it UNDER a skimmer sock, like this:

Poolmaster 16242 Poolmaster Skimmer Basket Liner (http://www.amazon.com/exec/obidos/ASIN/B004XUIRQW/poolbooks)
to keep from fouling it.

However, it's unproven. We think it probably works; but we're not sure how well, or what limitations may apply. Periodic's owner is a genuine PhD chemist but is playing things very close to the chest, and is really hoping to make a killing off his patent.

PAC should work, but will require regular attention to the filter, careful filter cleaning, and either many repeated small doses or jury rigged trickle feed into a skimmer.

Cal hypo oxidation onto the filter works, but is potentially dangerous (cal hypo does NOT play well other other chemicals - so NO feeders or devices or chemicals in the skimmer or the lines between the skimmer and the filter).

JimK

05-20-2012, 10:34 PM

+ Borax is about $0.65 - 0.75/lb at Walmart.

Thanks. I'll check out the local prices here.

+ A "natural" stain fighter could be a chitin (shrimp shell) product OR it could be a mined ortho-phosphate. Better not.

Sorry, are you saying I shouldn't use this brand of salt? What's the likely consequence of using it if it contains the things you mention? I've already used one 40lb bag of this in my pool. Am I likely to have some kind of problem? I bought 200lbs to have on hand for the season. Should I return it and go back to the brand I was using (I think they still carry it)?

+ Purple Stuff is one of 3 Jack's products that are HEDP, a chlorine resistant phosphonate. These eventually break down to ortho-phosphates and release the chelated metals.

I guess this explains the need for a regular maintenance does (add 12 ounces a week works to maintain the recommended level). I did know it breaks down into some kind of phosphate, but I was told it's not the same kind of phosphate that algae feeds on. Is this correct?

+ There are 3 possible strategies for removing metals:
=> CuLater zeolite-like patented product. Maker *claims* that it will remove phosphonate chelated metals. Available from Amazon:

1 ppm Culator, direct from Amazon (http://www.amazon.com/exec/obidos/ASIN/B003C5PNUW/poolbooks)
1.5 ppm Culator, sold by Amazon, shipped from Periodic (http://www.amazon.com/exec/obidos/ASIN/B004Y6RK3Q/poolbooks)
4 ppm Culator, sold by Amazon, shipped from Periodic (http://www.amazon.com/exec/obidos/ASIN/B007AHDMTM/poolbooks)

=> Flocculant use -- PAC (polyaluminum chloride) dosed slowly pre-filter should gradually remove metals.

GLB Pool & Spa Products 71408 1-Quart Drop n' Vac Pool Water Clarifier @ Amazon (http://www.amazon.com/exec/obidos/ASIN/B0002KT6TY/poolbooks)

=> Oxidation onto the filter with calcium hypochlorite.
(I've done this myself, repeatedly. But it's method dependent and if you are not careful, can result in stains.)

OK. Those are the options, but each as problems.

CuLator is zero risk and very easy; you can use it simultaneously with HEDP, and (reportedly) remove the metals while still protecting your pool with HEDP, because (reportedly, again) the CuLator material has a higher affinity for the metals than HEDP. But, it's unproven, and intrinsically slow, since you must pass all of the pool water over this little baggie sitting in your skimmer. You'd probably want to use it UNDER a skimmer sock, like this:

Poolmaster 16242 Poolmaster Skimmer Basket Liner (http://www.amazon.com/exec/obidos/ASIN/B004XUIRQW/poolbooks)
to keep from fouling it.

However, it's unproven. We think it probably works; but we're not sure how well, or what limitations may apply. Periodic's owner is a genuine PhD chemist but is playing things very close to the chest, and is really hoping to make a killing off his patent.

PAC should work, but will require regular attention to the filter, careful filter cleaning, and either many repeated small doses or jury rigged trickle feed into a skimmer.

Cal hypo oxidation onto the filter works, but is potentially dangerous (cal hypo does NOT play well other other chemicals - so NO feeders or devices or chemicals in the skimmer or the lines between the skimmer and the filter).

Ugh........it almost sounds easier to just keep using the Purple Stuff. I've been using it for several seasons and haven't noticed any negative effects, well maybe a little to my wallet.

I'm curious about the cal hypo method. Could you elaborate?

Thanks.

PoolDoc

05-20-2012, 10:42 PM

Hi Jim;

The CuLater is as easy as it gets -- if it works.

The cal hypo method depends on simultaneously oxidizing the metals and precipitating calcium carbonate onto the filter to trap the metals. It will NOT work while you have functional levels of phosphonates in the water. It WILL make things go 'BOOM' if you have a feeder or something else that allows undissolved cal hypo to contact almost any other pool chemical.

One more point to consider: if you do have an input source of metals, the phosphonates will eventually fail. If you don't have an input source -- you may have ALREADY removed the metals, and don't actually need the phosphonates any longer.

JimK

05-20-2012, 11:28 PM

Hi Jim;

The CuLater is as easy as it gets -- if it works.

I did some searching on that product. Some of the reviews on Amazon indicates the manufacturer recommends replacing the product every couple weeks. That would make it twice as expensive or more, depending on the particular CuLater used, that what I'm using now. And if I am adding metals every time I add salt, then I would have to use the product on a continual basis which gets expensive really quick, much more so than I'm spending now.

The cal hypo method depends on simultaneously oxidizing the metals and precipitating calcium carbonate onto the filter to trap the metals. It will NOT work while you have functional levels of phosphonates in the water. It WILL make things go 'BOOM' if you have a feeder or something else that allows undissolved cal hypo to contact almost any other pool chemical.

Sounds like that method is way above my skill/knowledge level, so I think I'll forget about that idea.

One more point to consider: if you do have an input source of metals, the phosphonates will eventually fail. If you don't have an input source -- you may have ALREADY removed the metals, and don't actually need the phosphonates any longer.

That brings up a couple points where I remain unclear;

1. Is it true my SWCG is the cause of the problem, as I was told, by separating out the trace amounts of iron present in the salt? BTW, I have two coworkers who also use a SWCG (one has a vinyl pool like mine, and the other a fiberglass pool), and they both have the same issue, making me think the SWGC process may actually be the issue. Your thoughts?

2. Is the Purple Stuff actually allowing the filter to capture the metals as quoted here on their website "...The stain removers will lift the stain off the surface, but its The Blue, Pink, Purple, or Magenta Stuff that will remove the metals from the pool and into the filter..." so when I backwash I'm getting rid of the collected metal?

3. So if the salt is the source of metals and the chlorine generation process is separating it out so it can attach to the pool surfaces, are you saying the Purple Stuff at some point will stop working? Or am I likely removing the metals at a rate that will allow the Purple Stuff to keep working as long as I keep up with the maintenance doses?

Perhaps my next step should be to have my water tested for metals. Can I test for iron, copper, etc. myself, or should a have a pool store test it for me? Does the use of the Purple Stuff prevent getting accurate results?

Sorry for all the questions. I greatly appreciate all the help sorting this out.

PoolDoc

05-20-2012, 11:42 PM

Some of the reviews on Amazon indicates the manufacturer recommends replacing the product every couple weeks. That would make it twice as expensive or more, depending on the particular CuLater used, that what I'm using now..

Yeah, manufacturers do that sort of thing.

Remember, I told you that my impression of the Periodic guy is that (a) he's a real chemist and (b) he REALLY wants to make a financial killing.

However, if the CuLater does not get fouled with oils and such, based on the chemical mechanism described, it should work indefinitely. Obviously, that wouldn't fit well with the Periodic guys plans to get rich, so it's not real likely he's going to tell you that.

What's happened with these sorts of products in the past is that somebody discovered a perfectly valid niche product like Culator, but then discovers that a pool niche product will NEVER make him rich, so he tries to force EVERYONE into the niche. I suspect that's happening here.

Can I test for iron, copper, etc. myself, or should a have a pool store test it for me? Does the use of the Purple Stuff prevent getting accurate results?

+ We think HEPD interferes with most metal tests, but we're not sure. Taylor has not been really helpful on this.
+ Pool stores are almost certainly worse than the testing YOU can do.

JimK

05-21-2012, 12:15 AM

Yeah, manufacturers do that sort of thing.

Remember, I told you that my impression of the Periodic guy is that (a) he's a real chemist and (b) he REALLY wants to make a financial killing.

However, if the CuLater does not get fouled with oils and such, based on the chemical mechanism described, it should work indefinitely. Obviously, that wouldn't fit well with the Periodic guys plans to get rich, so it's not real likely he's going to tell you that.

What's happened with these sorts of products in the past is that somebody discovered a perfectly valid niche product like Culator, but then discovers that a pool niche product will NEVER make him rich, so he tries to force EVERYONE into the niche. I suspect that's happening here.

Not sure if I want to try an unproven product, but if I decide to try it, which one should I try that would give me the best chance of good results for the buck, 1ppm, 1.5ppm, or 4ppm? Would it make sense that the 4ppm one would last much longer than the 1ppm or 1.5ppm? BTW, according to their website, they recommend replacing it every month (perhaps the every two weeks recommendation in the Amazon reviews was for stain removal? Currently I have no stains). If what you said about lasting indefinitely (seems like at some point it would get saturated?) is correct, I'm wondering if I can get by with just using one per season. That would save me money over using the Purple Stuff.

+ We think HEPD interferes with most metal tests, but we're not sure. Taylor has not been really helpful on this.
+ Pool stores are almost certainly worse than the testing YOU can do.

So it sounds like I may not be able to get accurate results regardless if I test myself (what kit would I need to buy?) or if I have a pool store do it. Might I at least be able to tell if I have any metals or not even if the actual level isn't clear?

Also, are you able to comment on these items I mentioned in my previous post?

1. Is it true my SWCG is the cause of the problem, as I was told, by separating out the trace amounts of iron present in the salt? BTW, I have two coworkers who also use a SWCG (one has a vinyl pool like mine, and the other a fiberglass pool), and they both have the same issue, making me think the SWGC process may actually be the issue. Your thoughts?

2. Is the Purple Stuff actually allowing the filter to capture the metals as quoted here on their website "...The stain removers will lift the stain off the surface, but its The Blue, Pink, Purple, or Magenta Stuff that will remove the metals from the pool and into the filter..." so when I backwash I'm getting rid of the collected metal?

3. So if the salt is the source of metals and the chlorine generation process is separating it out so it can attach to the pool surfaces, are you saying the Purple Stuff at some point will stop working? Or am I likely removing the metals at a rate that will allow the Purple Stuff to keep working as long as I keep up with the maintenance doses?

Thanks again!

JimK

05-21-2012, 01:08 AM

waterbear

05-21-2012, 02:21 AM

A few observations:
a 4.75 lb box of borax is $2.99 at walmart, target, and the local grocery store.
SWCGs do not cause staining. However, if you do not watch your pH and allow it to spike that can cause staining (and is usually what DOES precipitate stains.) If you know of two other people near you that have similar problems it is either the salt they are using (not very pure) or it's your water. Even city water can have iron in it.

While solar salt might take a bit longer to dissolve compared to a fine grained pool salt it tends to be very pure and rarely causes staining problems. I have seen 'pool salt' sit on a a pool floor and leave a stain behind. I have never seen solar salt do that. The fact that a pool salt has to include a stain fighter should tell you something. My suspicion that the 'natural stain fighter' is citric acid since that is was is often included in water softener pellets to 'clean' the units. Your expensive pool salt might be no more that ground up water softener pellets.

HEDP does not allow a filter to filter out the metals but this claim is often made. It chemically 'deactivates' the metal ions so they become non reactive for a while. The metal stays in the water until you either replace the water or it drops out of solution as a stain. If the stain is on a filter medium it is possible to change the medium and remove the metal.
The phosphates created by the breakdown of metal sequestrant are exactly the same ones that are 'algae food' but high phosphate levels do not mean you will have algae and are often NOT the limiting factor. Algae also need nitrate. However, there is no easy way to remove nitrate from pool water other than replacement of the water so a profit cannot be made by selling a product as it can with so called phosphate removers.

JimK

05-21-2012, 11:49 AM

A few observations:
a 4.75 lb box of borax is $2.99 at walmart, target, and the local grocery store.

That's much lower than the what I found online. I'll have to check out the local stores next time I need some.

SWCGs do not cause staining. However, if you do not watch your pH and allow it to spike that can cause staining (and is usually what DOES precipitate stains.) If you know of two other people near you that have similar problems it is either the salt they are using (not very pure) or it's your water. Even city water can have iron in it.

I do keep a close watch on PH (test at least every other day if not everyday) and I don't let it get above 7.8. Could there be short spikes in between? Seems like if short undetected spikes are occuring, that the staining would suddenly appear, but it doesn't. It happens gradually over time. (Note; as I mentioned earlier, I've not had any staining since adding The Purple Stuff to my maintenance routine several seasons ago.)

I know 6 people in my area that have pools including myself (5 vinyl, 1 fiberglass). Out of the 6, 3 of us use the same SWCG system (we had our pools installed within a couple years of each other) and the other 3 use traditional chlorination methods. Those of us who use a SWCG have had metal staining issues and the others have not (we are all on the same city water supply). This in combination with the fact that staining doesn't occur when the system isn't running (ie - during the winter) leads me to believe there must be something to what I was told, that the SWCG separates out the impurities in the salt (which is what I suspect is the source of iron). It's also interesting that our iron staining issue followed the same pattern; 1st season no staining, 2nd season occasional staining, 3rd season staining more frequent, and so on. Perhaps I am missing or misunderstanding something?

While solar salt might take a bit longer to dissolve compared to a fine grained pool salt it tends to be very pure and rarely causes staining problems. I have seen 'pool salt' sit on a a pool floor and leave a stain behind. I have never seen solar salt do that. The fact that a pool salt has to include a stain fighter should tell you something. My suspicion that the 'natural stain fighter' is citric acid since that is was is often included in water softener pellets to 'clean' the units. Your expensive pool salt might be no more that ground up water softener pellets.

I have noticed that the label on the salt bags say they're 99.9% pure. Not sure if solar salt is more pure, or perhaps the pool salt has additives that aren't listed on the label? If the salt I currently have is using citric acid (ascorbic acid) then I'm fine with that. However, Ben mentioned it may contain "chitin (shrimp shell)" or "a mined ortho-phosphate" and seemed to suggest that I should avoid that. Perhaps I'll contact the manufacturer to see if they will tell me what they are using before I lug all that salt back to the store.

HEDP does not allow a filter to filter out the metals but this claim is often made. It chemically 'deactivates' the metal ions so they become non reactive for a while. The metal stays in the water until you either replace the water or it drops out of solution as a stain. If the stain is on a filter medium it is possible to change the medium and remove the metal.
The phosphates created by the breakdown of metal sequestrant are exactly the same ones that are 'algae food' but high phosphate levels do not mean you will have algae and are often NOT the limiting factor. Algae also need nitrate. However, there is no easy way to remove nitrate from pool water other than replacement of the water so a profit cannot be made by selling a product as it can with so called phosphate removers.

That's what I remember reading somewhere before. In season 2 (2005) when I was having problems with the liner getting slick frequently despite FC being around 7, my pool store tested for phosphates and found they were high. He said with high phosphates algae will grow despite good FC levels. Ever since then I use a phosphate remover in my closing routine that comes with the closing kit for mesh cover users. I use a solid cover now (MUCH easier spring cleaning!), but still get the mesh cover kit and apply the phosphate remover at closing as a precaution.

I would like to check my water to see if I still have metals and still need the sequestrant (I've been using The Purple Stuff for several years now), but according to Ben, it's seems sequestrants may interfere with the test results. So I guess the only way to find out if I still have metals (likely if the source is the salt as I suspect) is to stop using the sequestrant and see if staining returns. However, I really don't want to do that as getting rid of the stains is a royal pain and expense.

All this discussion has been very interesting and educational, although sometimes confusing to me. Lately I've been thinking about my current routine and how it might be made cheaper and easier, if possible. It has taken me some years to come up with my current routing which is working very well for my pool (no more staining or algae issues; pool always looks great), so I may come across as a little reluctant to change, and perhaps I am. Sorting though a mountain of information, and misinformation (!), has been challenging.

In the end it seems I'm down to two potential areas that might help me reduce costs and associated questions I need to answer;

1. Stain control. Can I safely stop using the Purple Stuff, or will I always need some sort of stain control (my suspicion is I will)? If I need stain control, is their a better/less expensive way? Would using different brand of salt help?
2. Algae control. Can I stop using polyquat and just rely on borates and chlorine? Looks like switching from "Optimizer" to 20 Mule Team Borax would net some savings.

It may turn out that my current routine is best for my pool and I should just stick with it.

waterbear

05-21-2012, 02:03 PM

PoolDoc

05-21-2012, 02:54 PM

I would like to check my water to see if I still have metals and still need the sequestrant (I've been using The Purple Stuff for several years now), but according to Ben, it's seems sequestrants may interfere with the test results. So I guess the only way to find out if I still have metals (likely if the source is the salt as I suspect) is to stop using the sequestrant and see if staining returns. However, I really don't want to do that as getting rid of the stains is a royal pain and expense.

You can do a bucket test.

1. Take a CLEAN white 5 gallon plastic bucket with a lid
2. Add 4 gallons of pool water.
3. Add 1/4 cup of plain 6% Clorox bleach (~200 ppm chlorine)
4. Mix, cover and wait 24 hours.
5. Uncover, and check for sediment.
6. Add 1/8 cup washing soda (sodium carbonate)
7. Mix, cover and wait 24 hours.
8. Inspect for sediment and stains.

The high chlorine should break down the phosphonates, and may drop out any metals. If not, the high pH (washing soda) should finish the job. Perfectly still water should allow it to settle. It take very little iron (less than 0.5 ppm) to make visible sediment. The clean white plastic should make any stains or sediment very visible. Use Clorox, since cheap bleach may have some iron or other metals. I know Clorox filters to prevent this; I think the others do, but using Clorox lets you be fairly sure.

Also, I'm going to ask Sean, of AutoPilot to take a look at this thread.

Meanwhile, can you add full pool info to your signature pump / filter / SWCG make and model? Link in MY signature to the settings menu.

JimK

05-21-2012, 03:19 PM

Using just 20 mule team borax and forgetting the polyquat is fine. I go on vacation every summer 9n July or August for about 2 weeks (and I live in Florida). I just shock the pool with bleach to about 20 ppm before I go (Borate 50 ppm, CYA 80 ppm) and turn everything off. When I come back I have never had a green pool. It might be slightly cloudy but no visible green. I turn on everythng, shock it again with bleach to 20 ppm, and by the next day am good to go. This has been my routine ever since I started using borate over 6 years ago.

Sounds like borax is very effective. I'll have to try it without the polyquat and see what happens. I may put that experiment off until next season since I already have a full seasons worth of polyquat on hand. Either that or find someone to sell it to!

You can probably cut way back on the HEDP if not stopping it all together. They say to add the maintenance dose weekly but often it is only necessary montly to prevent stain reoccurance. I would cut back to every two weeks and see of the setains stay away. IF they do after a few months then cut back to monthly.

Right now I'm adding 12 oz per week. If I cut back to every 2 weeks, do I still only add 12 oz, or do I add 24 oz? What about monthly?

I would have to say that it's the salt and not the SWCG. I have seen many pools that have never had staining issues with a SWCG. They have used water softener salt pellets or solar salt. Both are actually fine for use in a salt pool. The pellets are very slow to dissovle and can take over a day. The solar salt usually is gone in a few hours. Brushing helps any salt dissolve faster. I have seen several occurances of where pool salt was dumped in and not brushed and it left a stain where it sat. I have never seen that with solar salt.

I'm also pretty convinced that the iron is getting in the pool via the salt. BTW, I NEVER just dump salt into the pool or let salt sit on the bottom. I put the salt in a bucket, add water to pre-disolve most of it then add it throughout the pool. Perhaps I should switch to solar salt, it just takes so long to get it to disolve and I don't want it sitting on my liner. What do you think of this idea; put the solar salt in a large bucket, lower the bucket into the pool (pump running of course) and let it sit until the salt disolves/dispurses. This way I wouldn't have to keep brushing it around for what feels like forever. Would this work?

Citric acid is not the best additive for pool water even though it can be used like ascorbic acid to remove stains. It has some undesirable interactions. I had some info on this but 'get my hands on it at the moment.

Then it seems whatever "natural stain fighter" has been added to the salt I bought this season I shouldn't use it. I'll see if I can return it.

The only thing I would ADD to your routine is more brushing!

LOL.......yes, yes, I promise I'll do better!

The phosphate remover is a totally unneeded expense (and will get much more expensive soon if it hasn't already as China continues to raise the price on Lanthanum salts.) Don't waste any more money on it. You would be better served making sure the borate is 50 ppm before closing.

Thanks for the tip.

JimK

05-21-2012, 03:34 PM

You can do a bucket test.

1. Take a CLEAN white 5 gallon plastic bucket with a lid
2. Add 4 gallons of pool water.
3. Add 1/4 cup of plain 6% Clorox bleach (~200 ppm chlorine)
4. Mix, cover and wait 24 hours.
5. Uncover, and check for sediment.
6. Add 1/8 cup washing soda (sodium carbonate)
7. Mix, cover and wait 24 hours.
8. Inspect for sediment and stains.

The high chlorine should break down the phosphonates, and may drop out any metals. If not, the high pH (washing soda) should finish the job. Perfectly still water should allow it to settle. It take very little iron (less than 0.5 ppm) to make visible sediment. The clean white plastic should make any stains or sediment very visible. Use Clorox, since cheap bleach may have some iron or other metals. I know Clorox filters to prevent this; I think the others do, but using Clorox lets you be fairly sure.

Also, I'm going to ask Sean, of AutoPilot to take a look at this thread.

Meanwhile, can you add full pool info to your signature pump / filter / SWCG make and model? Link in MY signature to the settings menu.

Thanks, I'll give that a try. A question though, in step #6, is "washing soda (sodium carbonate)" the same as the bicarb (sodium bicarbonate?) that I use to raise TA?

I did put some of my pool info in my signature (can you see it?) the other day. I'll put the rest of the info in there as well. Not sure of the exact model of SWCG I have, but it's an Aquarite unit (Goldline) that uses the T Cell 15.

chem geek

05-21-2012, 04:27 PM

A question though, in step #6, is "washing soda (sodium carbonate)" the same as the bicarb (sodium bicarbonate?) that I use to raise TA?

No, those are related, but different. Washing soda (sodium carbonate) is what is in most "pH Up" products and raises both pH and TA. Baking soda (sodium bicarbonate) mostly raises TA with little change in pH (it can rise some depending on your starting pH). You use the former to raise both pH and TA at the same time and the latter to raise mostly TA only.

As for the CuLator replacement frequency, it depends on whether it fills up removing metals. You wouldn't replace it every couple of weeks unless you had a lot of metals in the water, the bag absorbed them (usually, but not always, coloring the bag), and you measured a drop in metal concentration but was still not low enough. Whoever described replacing it every couple of weeks was probably trying to make money from selling it, but even the manufacturer doesn't say to do it that frequently.

In fact, have you had your water tested for metal ion concentration? Such tests usually measure total concentration including metals bound to sequestrants when the dye in the test binds more strongly to the metal than the sequenstrant you are using. Ben's bucket test would be a more definitive test since it eliminates the sequestrant by reacting with it to release the metal.

By the way, having the FC that is 5% of the CYA level didn't come from me exactly. There was a user at TFP making careful measurements that found precisely for his pool where chlorine demand would start to increase from algae growth and then we looked at other user's SWCG pools at varying phosphate levels (when they knew them) and at some point proposed setting the lower standard since it seemed that the SWCG pools were able to prevent algae growth at the lower FC/CYA level. My contribution was for the FC/CYA ratio being consistent across CYA levels and initially I proposed a 4.5% setting but that level was based on actual pool reports, not on theory. 5% is the rounded version of that which ended up in the recommendation tables as 3 ppm FC for 60 ppm CYA to 4 ppm FC for 80 ppm CYA. I also looked at the chemistry of the SWCG cell to figure out that there would indeed by super-chlorination of a portion of the water in the cell that was different than occurs from manual dosing (the difference being the pH, at least initially).

PoolDoc

05-21-2012, 05:04 PM

You wouldn't replace it every couple of weeks unless you had a lot of metals in the water, the bag absorbed them (usually, but not always, coloring the bag), and you measured a drop in metal concentration but was still not low enough. Whoever described replacing it every couple of weeks was probably trying to make money from selling it, but even the manufacturer doesn't say to do that.

The mfg is saying every 30 days (4 weeks):

Discard used PowerPak after 30 days. (Note: PowerPak contents MAY change color.) from
http://www.culator.com/eliminating-metals

JimK

05-21-2012, 06:28 PM

No, those are related, but different. Washing soda (sodium carbonate) is what is in most "pH Up" products and raises both pH and TA. Baking soda (sodium bicarbonate) mostly raises TA with little change in pH (it can rise some depending on your starting pH). You use the former to raise both pH and TA at the same time and the latter to raise mostly TA only.

As for the CuLator replacement frequency, it depends on whether it fills up removing metals. You wouldn't replace it every couple of weeks unless you had a lot of metals in the water, the bag absorbed them (usually, but not always, coloring the bag), and you measured a drop in metal concentration but was still not low enough. Whoever described replacing it every couple of weeks was probably trying to make money from selling it, but even the manufacturer doesn't say to do it that frequently.

Thanks for the clarification.

In fact, have you had your water tested for metal ion concentration? Such tests usually measure total concentration including metals bound to sequestrants when the dye in the test binds more strongly to the metal than the sequenstrant you are using. Ben's bucket test would be a more definitive test since it eliminates the sequestrant by reacting with it to release the metal.

I have not had my water tested. I thought I understood that the sequestrant I'm using interferes with such tests. Is this incorrect? Is there a specific test kit that will give me accurate results even with the sequestrant? I plan on trying Ben's bucket test, but it would be nice to know the level of metals I'm dealing with.

By the way, having the FC that is 5% of the CYA level didn't come from me exactly. There was a user at TFP making careful measurements that found precisely for his pool where chlorine demand would start to increase from algae growth and then we looked at other user's SWCG pools at varying phosphate levels (when they knew them) and at some point proposed setting the lower standard since it seemed that the SWCG pools were able to prevent algae growth at the lower FC/CYA level. My contribution was for the FC/CYA ratio being consistent across CYA levels and initially I proposed a 4.5% setting but that level was based on actual pool reports, not on theory. 5% is the rounded version of that which ended up in the recommendation tables as 3 ppm FC for 60 ppm CYA to 4 ppm FC for 80 ppm CYA. I also looked at the chemistry of the SWCG cell to figure out that there would indeed by super-chlorination of a portion of the water in the cell that was different than occurs from manual dosing (the difference being the pH, at least initially).

Thanks for the explanation. That gives me confidence that I've been using appropriate FC levels.