TA opposed to PH

by Bill Pike
(Virginia Beach, VA USA)

Commercial pool total alkalinity vs. pool pH level...


I operate several pools both indoor and outdoor. I have one outdoor pool that I have been having an ongoing issue with.

The pH stays high 7.8 - 7.9 while the total alkalinity is low 30 - 40 ppm. Anything I do to try to raise the TA of course raises the PH, any advise?

The pool is a commercial (hotel) at 90,000 gallons the current temp is around 77. The later Summer temps will be up around 80 - 87.

Thanks for your questions Bill

The YMCA pool is 80,000 gallons so we're pretty close to your commercial pool. The pH level of our fill water runs 8.0ppm and the total alkalinity is 30ppm so I have the same issue as you.

Hopefully you are using a Reagent FAS-DPD K-2005or 2006 test kit.

Swimming Pool Water Testing Kit..Chlorine Level..Chemistry..

First you'll want to lower the pool pH level. I found that 1 gallon of acid reduces the Y's pool by 0.2ppm. You may want to use 1 1/2 gallons, but there's a way you need to do it so it won't affect the alkalinity too much.

You can go to this link and find exactly how I do it.

Swimming Pool pH Levels..Chemistry..Alkalinity..Water..Care

The short of it is to put the acid around the perimeter of the pool starting at the deep-end and the filtration running. If you have any water features you need to turn them on to help with aeration. Keep the water moving when decreasing a pool's pH level.

Wait for one complete turn-over of the water. Usually state law requires a complete turn-over every 6 - 8 hours with about 240 - 280 gallons per minute (GPM).

Once the pH level is around 7.2ppm it's time to raise the total alkalinity. I have always used sodium bicarbonate and it works very well.

Pool Alkalinity In Swimming Pools...Chemistry..Care..pH..Cloudy Pool Water.

Adjust Your Total Alkalinity..Pool Water Maintenance..Care..Chemistry..Quality..

Turn the filtration off and put the bicarb in one place in the deep-end. With the Y's pool it takes about 200oz. of bicarb to raise the alkalinity 10ppm.

Allow this to sit for 2 - 3 hours, turn the pump filter back on, and wait for 1 complete turn-over.

Re-test the pH and alkalinity and make another adjustment.

Keep testing and going back and forth with the pH and TA until you reach your goal of 7.6 - 7.8ppm for the pool pH level and 80 - 100ppm for the total alkalinity.

This works for me every time.

Thanks again

Robert



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May 31, 2014
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Alkalinity And pH: A Vicious Cycle
by: Dany

I live in NY and have a pH-TA problem. Here are my pool specs: in-ground, 21K gal, TA low (60), Chlorine high (4.5) pH high (8.0), water still greenish. The local pool store has dragged me into a pH-TA vicious cycle. They claim that because my pH is too high, chlorine can not be effective: makes total sense, so they make me buy pH minus. Wait 48h, retest. Then TA is too low, buy Alkalinity ($$). Wait 48h, retest. pH too high, chlorine not effective. Buy pH minus, wait 48h retest, add chlorine because it has dissipated, wait 48h, retest, buy more alkalinity...then redo the scheme until you're broke. Meanwhile, the water has not gotten any better...I've been looking around at different forums unsuccessfully...please advise! Thanks! Dany





Thanks for the question

I had this problem with high pH (8.2) and low TA (30) with the fill water at the YMCA pool. This is how I did it. Add the acid around the perimeter of the pool, allow to filter for 10 hours, then retest the pH and TA. The TA may be lower and that's alright. It's 0.8 qrts. of acid to lower the pH 0.2 per 10,000 gallons. I'd use 1/2 qrt or 16 oz. for your pool right now.

Baking soda to raise the TA. You don't need TA Up or pH Up, just baking soda. It's about $4.99 for 4 lbs. Turn the pump off and add the bicarb in the deep end. Allow to sit for 4 - 5 hours, turn the pump back on, filter for 10 hours then retest both the pH and TA. It's 1 lb. of bicarb to raise the TA 10ppm per 10,000 gallons. Very important to go slow and incrementally.

Your TA is not too far off. The range is 80 - 100ppm. The pool store employee is correct that chlorine is more effective at a lower pH level.

Let me know how it turns out for you.

If you feel your situation is more complex than this, I do phone consultations for a donation of your choice. It makes things go much faster and many people have found it extremely beneficial, saving them time and money in the long run. All your questions will be answered. I have nothing to sell you so you know I'm not bias.

Pool Consultation

Hope this helps and have a great Summer.

Robert

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