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Great site. Just installed a salt chlorinator system here in northern Alabama. I can't wait for warm weather. All is working wonderfully, but I would like to read about the problems I can expect. Just want to stay up with issues. Is there a forum thread that is toward that end? And, are there any BBB ideas that I can use with this system?
An SWCG -- salt water chlorine generator -- is just a METHOD of chlorine, so almost everything applies.
The biggest complaint by many SWCG owners, including myself, is PH rise. This can be controlled some by lowering TA unless you have high TA fill water with high evaporation like myself and then you will need lots of acid.
I'll second that, but I prefer adding acid weekly over adding bleach daily!Quote:
Originally Posted by mas985
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.
My appologies to the OP for being off topic, but his item caught my attention.Quote:
Originally Posted by waterbear
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.
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.Quote:
Originally Posted by JimK
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 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.
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.
(testing addition of signature)
It's there!