Borate application, redux

[chem geek]

There are plenty of spa owners at poolspaforum.com who use the Dichlor-then-bleach method (Dichlor used initially for about a week to build up CYA and then switch to bleach) and are able to keep their pH and TA fairly stable by having the TA be low (usually 50 ppm or a little lower), using 50 ppm Borates, and not trying to keep the pH much below 7.8 though some find the pH to be OK in the 7.5 to 7.7 range. Now keep in mind that these are residential spas so typically not used more than once a day. The water stays in good shape for about twice as long as Dichlor-only users (probably due to CYA build up making chlorine less effective). I would not characterize them as cesspools though it is true that they build up some organics that are not fully oxidized but the only indicator of that is a slowly increasing chlorine demand from around 25% per day to 50% per day. Ozonators are a mixed bag, but for high-use spas they help while for low-use spas they mostly just increase chlorine demand.

[PoolDoc]

If you have a pH of 7.8, a TA of 50 ppm, a borates of 50 ppm and a CYA of 40ppm(?), I'm assuming you'll have a very low CA? And thus, you'll have little pH drift from CO2 off-gassing during periods of aeration?

Are you / they adding dichlor (CYA) to spas because they are uncovered outdoor spas, or to reduce DPB formation? I get the "don't let CYA build up" thing.

So, I can see strategy of high pH + low CA + elevated non-CA TA + CYA control as a reasonable effort.

Can those results be improved by using that strategy, except switching to a very high CYA plus very high Cl residual? Something like 200ppm CYA plus 25 ppm Cl as a normal level? That might overcome the problem of insufficient total chlorine residual (in 300 gal water) to react with the bather goop of a couple of spa users.

-----

I've also realized I don't have any idea of what the 'normal' spa configuration is. In my area, even today, most spas are detached. But, I gather that attached spas may be more the norm in California and Florida.

- Are most of these in a shared equipment / unshared water configuration?
- Spill-over spas have to be in at least partially shared water configuration. Is it typically 100% shared, or partially shared?

I'm going to need to see if I can find some piping and control layout diagrams for these spas, to see have they've been design and should operate.

[waterbear]

If you have a pH of 7.8, a TA of 50 ppm, a borates of 50 ppm and a CYA of 40ppm(?), I'm assuming you'll have a very low CA? And thus, you'll have little pH drift from CO2 off-gassing during periods of aeration?

At PoolSpaForum we tend to recommend (with the Dichlor/Bleach method in an acrylic portable spa or one unattached to the pool with either dual or shared pump/filter so they are two separate bodies of water) TA of 50-60 ppm, borate of 50 ppm, CH about 130-150 ppm or higher (depending on how hard the fill water is, if the fill water is soft we don't recommend raising it above about 130-150 ppm since that amount of hardness is enough to deter foaming), and achieve a CYA level of 20-30 ppm by using dichlor and then switching to bleach for chlorination and shocking until time for the next drain and refill with spas (every 3-6 months,depending on usage). With a plaster inground spa with it's own plumbing, pump, and filter (either stand along or single/dual equipment with an unattached pool we basically keep the same recommendation but raise the CH to keep the SI in proper range. With a shared pump filter system with a spillover spa you essentially have a single body of water and one pump and filter. There might be a secondary filter or blower for the jets much like water features in a pool might ave a secondary filter but the main circulation is a single system and the spa is only isolated when being brought up to temperature and then used. This tends to be the most common configuration with both plaster and fiberglass pools and either plaster, fiberglass, or acrylic spas. This is essentially a pool with high aeration, not that much dfferent than a negative edge pool or a pool with water feature and running a low TA and maintaining the pH at a higher level and also adding 50 ppm borate is an effective way to minimize and slow pH rise and obtain pah stability for a longer period of time. It also requres a bit more attention to water parameters, testing and dosing. Adding a SWCG to the mix adds its own unique set of problems to minimize cell on time (by keepign CYA at the max) to lessen the aeration effect caused by hydrogen bubble generation and thereby also slowing the outgassing of CO2.

Are you / they adding dichlor (CYA) to spas because they are uncovered outdoor spas, or to reduce DPB formation? I get the "don't let CYA build up" thing.

Most portable spas are kept covered to maintain the heat and keep energy bills down,particularly since many are used in northern climates when pools are normally closed (We tend to be busiest at the forum in the dead of winter and have a LOT of Canadian and northern US members!). The idea of using a small amout of CYA is because of, as Richard likes to describe it to the members there when explaining the dichlor/bleach method), its 'buffering' effect on chlorine (making it less aggressive). IF the spa is heavy usage then the addition of a decent ozone unit or the use of MPS is recommended to help oxidize organics.
This has turned out to be a huge improvement in the sole use of dichlor, which we have foundcan lead to outbreaks of pseudomonas and other water born illnesses as the CYA level gets higher and higher.

So, I can see strategy of high pH + low CA + elevated non-CA TA + CYA control as a reasonable effort.

Can those results be improved by using that strategy, except switching to a very high CYA plus very high Cl residual? Something like 200ppm CYA plus 25 ppm Cl as a normal level? That might overcome the problem of insufficient total chlorine residual (in 300 gal water) to react with the bather goop of a couple of spa users.

Interesting idea but then you have to get over the hurdle of convincing users that the high FC/CYA combination is not going to kill them of make them sick and there is the real concern that it could void the warranty on their spa.
-----

I've also realized I don't have any idea of what the 'normal' spa configuration is. In my area, even today, most spas are detached. But, I gather that attached spas may be more the norm in California and Florida.

- Are most of these in a shared equipment / unshared water configuration?

There are basically three configuations:
1. unattached dual equipment--the pool and spa are two separate bodies of water and each have their own pump, filter, heater, etc. Not that common because of equipment costs and now usually seen when there is an existng pool and a stand along portable spa is added to the mix.

2. unattached shared equipment (normally only found with automation--there is only one pump,filter, heater, etc. and the are valve actuators on timers that switch between pool and spa so each can have a filter cycle during they day but they are two separate bodies of water that are treated individually. Spas in this configuration are usualy kept at temperature and covered to maintain the heat.

3. attached pool/spa and shared equipment (spillover spa)--this is becoming the most common configuration since it minimizes equipment costs and simplifies water maintenance since it is essentially one body of water. Normal configuration is water enters spa, spills into pool, and to filter from pool skimmer and drain. The spa drains are off. There are often also returns in the pool that are active. When the spa is desired there are valves or actuators that shut off the pool skimmer, drain, returns and open the spa drains (shutting off the pool, stopping the spillover) and making the spa the only thing in the loop. The heater is turned on to bring the spa up to temerature, which normally does not take very long. In places like Florida heat pumps and solar are often all that is needed but in more northern climates gas or electric heat (either main or as a supplementary spa heater) is often needed.

Normal operation is as a single body of water at pool temperature and after the spa is used the water is essentially 'dumped and changed". The main problem is the higher aeration, which can be dealt with by lower TA, tighter pH control, and borate.

- Spill-over spas have to be in at least partially shared water configuration. Is it typically 100% shared, or partially shared?

100% shared. not sure how you could even have a partially shared configuration.

I'm going to need to see if I can find some piping and control layout diagrams for these spas, to see have they've been design and should operate.

Try this Hayward Aqualogic Prologic manual pages 9-11. It has some diagrams that might help. Dual systems and shared water (spillover) sihared systems do not have to be automated but many are. Systems that are unattached but share equipment are not really practical without some form of automation to control run times for the pool and spa.

[PoolDoc]

Waterbear, I changed your italic bold, because I couldn't read it; I need new glasses. Hope you don't mind.

Regarding partially shared spa/pool water, it can be done, but if it's not, there's no point in discussing it. (You learn a lot, having to deal with old commercial vacuum DE systems that are BELOW water level! It's not fun, climbing that learning curve, however.)

I see I need to add another category, so it is:
1. Non-concrete standalone spa. (low SI or low CA is OK; hi SI could scale heater.)
2. Concrete standalone spa (need balance SI to protect spa.)
3. Concrete attached; equipment share only.
4. Concrete attached with spillover or other water share.

But, something you said seemed to suggest that there may actually be a 5th category: non-concrete spa attached to a non-concrete pool. Are there such beasts?

The hydrogen bubble thing you mention is something I want to leave alone for the moment. Also, you describe buffer action in ways I wouldn't, but again, I'd like to leave that for later.

A point of curiousity: who IS poolspaforum.com? I was surprised to find that they've elected to use anonymous domain registration, which is unusual for businesses on the Internet.

You wrote

Interesting idea but then you have to get over the hurdle of convincing users that the high FC/CYA combination is not going to kill them of make them sick and there is the real concern that it could void the warranty on their spa.

Ok by me -- this is POOLForum, not PoolSpaForum. There are many more pool and more spa owners out there than PF + TFP + Havuz + PoolSpaF can serve, all together. (The shortage is in "answerers", not "askers"!) I'm willing to add spa help here, but I have ZERO desire to be a primary destination for spa owners.

So, if HiCYA + HiCl works, that is, that it can produce -- for the average spa owner -- water quality that is generally better and safer than otherwise, that's what I want to say here at PF. If they aren't convinced, that's fine by me. If HiC2 risks their warranty, my tendency would be to (a) warn them, (b) say, "your health and safety matters more than the warranty", and (c) you don't have to tell the company you're doing HiC2 -- it won't actually affect anything that matters from a warranty POV.

Also, reading through your post leaves me convinced that it's STILL not possible to provide people a "SpaSolution" that parallels, in quality, the "PoolSolutions" I developed. Since there are still unmet needs in the pool arena, that's what I'd prefer to focus on.

Thanks for the clarification on spa/pool arrangements. The shared water arrangement is the reason I have to change my attitude. It's seems to me that this configuration is, essentially, a pool with extra aeration, which you note.

There is one sanitation aspect to this layout: with low CYA/low Cl, the total mass of FC in the spa is not necessarily enough to oxidize the total mass of swimmer goo (if say, 4+ people get in, and the water is hot). This would result in a failure to sanitize, since the chlorine present would be reduced by the goo, leaving insufficient FC to rapidly kill bacteria and viruses shed by one or more spa users.

The very high turnover rate would ameliorate this issue to a degree, since fomite associated bacteria and viruses would end up on the filter, leaving only planktonic pathogens present in the water.

Are you aware of any downsides to using DE in this setup? Doing so would improve sanitation, I think.

...........................

So far, having read some of Richard's stuff at TFP and elsewhere, and having read through your posts, I'm still inclined to say the best approach to take at PF, with respect to spas is:

1. Hi CYA + Hi Cl
2. Relatively low TA, composed of borates, cyanurates, and some carbonates, with VERY low CA.
3. Optimal pH at 7.8 - 8.2
4. Calcium adjusted to avoid scaling in the heater, but to bring the SI high enough to avoid plaster damage. However, on non-concrete setups, calcium can simply be left low.
5. Preference given to recommending DE filtration (unless you know a reason not to do so)
6. Caution given that HiC2 might void warranty, BUT they won't know unless spa owners tells, and that there's no reason to suspect that HiC2 damages anything.
7. Finally, when all is said and done, recognizing that spas cannot generally be as stable or sanitary as pools.
8. And, if "you don't want HiC2, go talk to Waterbear at PSF, and he'll explain other methods, there".

I feel like we need to offer pool owners the BEST method of sanitizing and managing their pool, not the one most acceptable to the Powers That Be. That's a call I made a long, long time ago when I started PoolSolutions, and not one I see any reason to change.

Of course, if there's some reason why HiC2 is NOT the best way, I need to understand that.

[chem geek]

Most spa users do not like soaking in a high FC (regardless of CYA level) because during the soak the ammonia from their sweat and urine forms monochloramine immediately (CYA doesn't slow that down very much) and some other organics such as creatinine also get oxidized and these all smell (dichloramine and nitrogen trichloride especially). Urea is slower to oxidize but for a longer soak its oxidation by-products could also smell. So the recommendation is instead to add enough chlorine RIGHT AFTER one's soak such that they measure a small residual of 1-2 ppm FC just before their next soak. So yes, during a soak the FC will get towards 0 during part of the soak, but it will be for a short time and there will be a small amount of monochloramine (not more than 1-2 ppm) there to inhibit bacteria. Even if there wasn't, bacteria take 15-60 minutes to double in population even under ideal conditions so in practice the blast of high chlorine right after the soak kills them off and prevents biofilm formation. So the only risk with this approach is that one does not have the fast kill times to prevent person-to-person transmission during part of the soak, but in residential spas this is not normally an issue. One could not use this approach in commercial/public spas.

The key to having the spa be well-maintained is adding sufficient chlorine after a soak to oxidize all of the bather waste. A rough rule-of-thumb when there is no ozonator is that every person-hour of soaking in a hot (104ºF) spa requires 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of MPS in order to oxidize the bather waste. Of course, one should adjust their dosing such that they measure 1-2 ppm FC just before their next soak -- the rule-of-thumb is just that and not an absolute dosing amount so one should adjust accordingly.

For those who do want some protective FC level during their soak, they can still use this method but target a higher FC level for the start of their soak and yes one could have a somewhat higher CYA level to compensate for that. However, for most residential spas, one doesn't need to get much higher than 4 ppm FC or so. In a 350 gallon spa, one person-hour would be 7 ppm FC to oxidize bather waste, but the urea is slower to oxidize so in practice one doesn't need that full amount in order to maintain FC throughout a normal soak time. Again, one can simply target whatever FC they need to start a soak such that at the end of the soak they still measure some residual FC (a least 1 ppm). Most people don't do this because they would rather have a clean-smelling soak and understand the risk of person-to-person transmission in their own spa with (typically) their own family is low.

[waterbear]

Pressed for time now so I will just respond to a few points.

Waterbear,

But, something you said seemed to suggest that there may actually be a 5th category: non-concrete spa attached to a non-concrete pool. Are there such beasts?
Yes, I have a fiberglass pool and acrylic spa myself. However, there is emprical evidence that higher calcium in a fiberglass pool helps inhibit staining so I run my calium acording to the SI recommended for plaster. Since doing so I have had no staining. If I let it drop the fiberglass yellows and I have to break out the ascorbic acid.
The hydrogen bubble thing you mention is something I want to leave alone for the moment.
Yet, this is the main reason to run CYA at max in a salt pool. It does slower the pH rise from outgassing of CO2.
Also, you describe buffer action in ways I wouldn't, but again, I'd like to leave that for later.
Just trying to put it in terms that the ordinary reader would understand, It is a difficult concept to grasp properly and there is just not really a good analogy that I have been able to come up with. Chemgeek's spring analogy is good but even he said that it was not really right and I do agree.
A point of curiousity: who IS poolspaforum.com? I was surprised to find that they've elected to use anonymous domain registration, which is unusual for businesses on the Internet.
They publish a pool/spa magazine with paid advertising but the forum is pretty much on it's own except for the mods (and as far as I can tell there are only two of us active) and a lot of experimentation with methods of spa care (way beyond the usual dealer's "drop a few bromine tabs in a floater and forget about it") and some workable spa care methods have come out of this, mainly dichlor/bleach, 3 step bromine (sodium bromide to create bank AND tabs in a floater) with bleach as the oxidizer, and silver/MPS/hot water such as N2 Spa (the pool N2 is a different animal altogether) and Silspa from Njonas.
You wrote
Ok by me -- this is POOLForum, not PoolSpaForum. There are many more pool and more spa owners out there than PF + TFP + Havuz + PoolSpaF can serve, all together. (The shortage is in "answerers", not "askers"!) I'm willing to add spa help here, but I have ZERO desire to be a primary destination for spa owners.
However, the OP that started this all is not a spa owner but really a pool owner with a high aeration pool and a SWCG, different animal than a spa owner! Let's remember this fact.bold type for emphasis

Also, reading through your post leaves me convinced that it's STILL not possible to provide people a "SpaSolution" that parallels, in quality, the "PoolSolutions" I developed. Since there are still unmet needs in the pool arena, that's what I'd prefer to focus on.

Thanks for the clarification on spa/pool arrangements. The shared water arrangement is the reason I have to change my attitude. It's seems to me that this configuration is, essentially, a pool with extra aeration, which you note.

There is one sanitation aspect to this layout: with low CYA/low Cl, the total mass of FC in the spa is not necessarily enough to oxidize the total mass of swimmer goo (if say, 4+ people get in, and the water is hot). This would result in a failure to sanitize, since the chlorine present would be reduced by the goo, leaving insufficient FC to rapidly kill bacteria and viruses shed by one or more spa users.

The very high turnover rate would ameliorate this issue to a degree, since fomite associated bacteria and viruses would end up on the filter, leaving only planktonic pathogens present in the water.

Are you aware of any downsides to using DE in this setup? Doing so would improve sanitation, I think.
No, and many installations do have a DE filter. I have a Cart myself. However, as you noted, in spa mode the turnover rate is very fast (I have a 150 sq in filter and 1 HP (full rated 2 speed) pump on a 280 gal spa! Once the system is put back into pool mode the water is basically dumped from the spa and into the pool.

Also, the SWCG is active in spa mode and runs at a lower output percentage (because of the automation). Not all systems allow this but many automation systems do. Simpler units such as the Pool Pilot (correct me if I am wrong, Sean) and the AquaRite used with manual valve sonly chlorinate in spillover mode because they lack the abiliyty to have two different output settings for pool and spa mode.
If we are talking about a manually chlorinated pool/spa then you are correct that the santizer will be depleted as the soak continues but this is really no different that what occurs in stand alone spas and, once again, the water will be 'replaced' after the pool is turned back on.
...........................

So far, having read some of Richard's stuff at TFP and elsewhere, and having read through your posts, I'm still inclined to say the best approach to take at PF, with respect to spas is:

1. Hi CYA + Hi Cl
2. Relatively low TA, composed of borates, cyanurates, and some carbonates, with VERY low CA.
3. Optimal pH at 7.8 - 8.2
4. Calcium adjusted to avoid scaling in the heater, but to bring the SI high enough to avoid plaster damage. However, on non-concrete setups, calcium can simply be left low.
5. Preference given to recommending DE filtration (unless you know a reason not to do so)
6. Caution given that HiC2 might void warranty, BUT they won't know unless spa owners tells, and that there's no reason to suspect that HiC2 damages anything.
7. Finally, when all is said and done, recognizing that spas cannot generally be as stable or sanitary as pools.
8. And, if "you don't want HiC2, go talk to Waterbear at PSF, and he'll explain other methods, there".

I feel like we need to offer pool owners the BEST method of sanitizing and managing their pool, not the one most acceptable to the Powers That Be. That's a call I made a long, long time ago when I started PoolSolutions, and not one I see any reason to change.
I agree but you have to take into consideration pool/spa combos with or without SWCGs which really a a different animal than say a vinyl ingound or above ground pool and require a different approach because of some of the uniquie problems these pools have with pH stability.
Of course, if there's some reason why HiC2 is NOT the best way, I need to understand that.

I answered this quickly so I apologize in advance for any typos or spelling errors and I hope the italics is easer for you to read! I changed the color of my responses so they stand out.