High PH

[kirkdbjl]

I have a 15,000 gal pool and my PH is alway high. I have a salt generator and everything always tests in range with the exception of PH which is always high. Does salt keep it running high?

I put acid in regularly but the PH still reads high. How can I get the PH down and keep it ballanced?

[waterbear]

What is your TA? What is your CYA? ("in range" is not a test result reading. Posting a full set of test results NOT done with strips would be very useful to pinpoint exactly what is going on in your pool.) These are the two most important parameters in slowing pH rise in a salt pool. Make sure the CYA is at the manufacturer's recommended MAXIMUM (usually around 80 to 100 ppm, depending on the manufacturer of your unit). The rationale is that higher CYA will allow a shorter cell run time to maintain the desired FC level. This translated into less out-gassing of CO2 (caused by the production of hydrogen gas bubbles in the salt cell when it is on) which directly translates into slower pH rise. Which brings us to TA.

Your pool is over carbonated (this is what TA really is, a measure of bicarbonate in the water). By lowering the TA (to between 60-80 ppm) and raising the Calcium if needed to keep the saturation index in range (Important for plaster pools, possibly important for fiberglass pools, not important for vinyl pools) you will also slow the out-gassing of CO2 and therefore slow pH rise.
Out-gassing of CO2 is the MAIN cause of pH rise in swimming pools. Lower the TA (and therefore slow the out-gassing of CO2) and slow the pH rise.
Also, adding borates to 50 ppm (either by using a commercial product like Supreme or Optimizer) or by using borax and muriatic acid will introduce a secondary pH buffer system that effectively "locks" the pH at around 7.6 to 7.7 for extended periods of time.


Finally, what is the surface of your pool? Plaster pools (including aggregate finishes) often require more acid than other pool surfaces. This is the nature of the beast and if the plaster is less than a year old it is still curing and will require even more acid. All you can do is keep feeding it acid until the plaster is fully cured (normally about a year).

pH in any pool is never completely stable and will change. Aeration (out-gassing of CO2) causes pH to rise. The lower you put the pH the faster it rises (because you have converted more bicarbonate into carbonic acid--CO2 in water) so try and keep you pH no lower than 7.6 and lower it when it rises to 7.8 (once you drop the TA of course). You will get more pH stability than if you lower the pH more!

So, in a nutshell, to minimize pH rise in a salt pool:
1. raise CYA to the maximum, normally 80 ppm or 100 ppm depending on the manufacturer of your salt system.
2. Lower TA to 60-80 ppm (and adjusted calcium hardness upward if needed to maintain water balance.
3. Maintain pH between 7.6 to 7.8
4. (optional but highly recommended) add borates to 50 ppm.

It's really pretty easy but I will caution you that just doing one of these steps by itself probably won't have much effect. You really need to do all of them (at least the first 3) to really slow down the pH rise.

[DennyB65]

Waterbear, I am having these issues myself. I am in the process of gradually decreasing the TA with Muriatic acid as it is still at 130. CYA is at 50 so I will need to bring that up as well this weekend after cleaning the cart. I would really like to add Borates as you suggest, however, I have to admit that I am somewhat intimidated by the prospect as I have never dealt with them before. Is there a specific procedure that must be followed? Please advise. Full set of numbers are as follows: TC 4.0, PH 7.6, TA 130, CH 300, CYA 50. 12k gal aggregate finish with bottom jets and spillover spa.

[PoolDoc]

'Is it really possible to keep a "perfect" pool?'

Yes, if you mean a pool almost perfectly suited for swimmers and equipment.

No, if you mean the NSPI / NSPF / Pool Industry numbers.

Keep in mind, the pool chemical industry depends -- for more than 50% of its revenue -- on you (and millions of others) screwing up your pool. If you get it "right", per my first option above, you will hurt your pool store's revenue measurably. If everyone did that, they'd go broke. And, I mean that literally and actually, not metaphorically.

My BBB method is not primarily about "bleach, borax, and baking soda": it's about using just what you need, only what you need, from the most practical sources. Neither bleach nor borax are always the best choice, but it's ALWAYS better to use what you need, instead of what the pool stores want to sell you.

Ben

[DennyB65]

Ben,
I know that you speak the truth sir! This forum has been INVALUABLE to me over the years. You did not , however, answer my question. Please explain to me the procedure for adding Borax to my pool. Numbers are posted previously on this thread. Thank You in advance!

[CarlD]

Hey 'Bear! Nice to see you out of "hibernation"!
That was a great post on Salt water generator levels!

My pool is still closed but I'm hoping to start opening Saturday. First I have to move the filter wiring as we have a new deck extension. Then I recruit my teen to do the heavy lifting! I would have done it sooner but family issues and a cruise got in the way....