Fiberglass pool with TA and pH problems

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
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Fiberglass pool with TA and pH problems

Postby poolslave » Fri 03 Aug, 2007 01:50

I have a fiberglass over gunite pool with 24000 gallons. I have been told that the TA should be between 80 to 100 ppm and the pH between 7.4 to 7.6.
I have been having troubles in the past few weeks with the TA and pH.
The TA has been 130 ppm and the pH 7.0. I have added muriatic acid 3 cups at a time broadcasting it over the deep end of the pool. I wait 4 hours and add another 3 cups. I have added 1 gallon so far and the TA won't stay at 80 - 100 ppm it keeps going up to 130ppm. I have added granular chlorine to try to keep it clear. And I have added 5 pounds of soda ash to try and increase the pH.
Now the pool is very cloudy.

The pool place tells me to keep adding muriatic acid with the filter running at all times. They say that the TA is the most important thing to control in a fiberglass pool. That I actually should not do anything until the TA is lowered. I am concerned about the pH and chlorine levels.

I have read the suggestions on aerating to decrease TA, and letting the water sit for 30 minutes before adding the acid. I will try these suggestions, but I am not sure how much more to add or what to do next.

What would you suggest I do next?
Thanks for your help,

steve 101

Postby steve 101 » Sat 04 Aug, 2007 22:52

i work for leslies pool and if the rest of your chem is ok a level of 130 is fine, you just should bring that PH up. at leslies we sell soda ash which will do that you wont need anymore then 3-5lbs.


Postby Debprior » Mon 06 Aug, 2007 11:38

Thank you for the information. The Leslie pool store is the one that told me the total alkalinity was way to high at 130. This weekend I was able to get it down to 100 ppm but the pH went down to 6.8. I will add 5 pounds of the soda ash as you suggested and not worry about getting the TA lower than 120, then I will go back to Leslie's and let them know.
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Postby chem geek » Mon 06 Aug, 2007 12:02

You don't need to worry about the higher TA unless you have a big problem with the pH wanting to rise over time or if your CH is high and you are forming calcium carbonate scale. If you want to lower your TA, follow the procedure in this post as aeration with acid addition is the only way to lower TA quickly. You NEVER use pH Up if you want to lower the TA since pH Up is Sodium Carbonate and adds carbonates to the water which increase TA (beyond the normal increase in TA with pH).

The pool got cloudy with the pH Up because this increases both TA and pH which, if Calcium Hardness (CH) is also high, leads to cloudiness. You should get yourself a good test kit, the Taylor K-2006 from Taylor here or from Leslie's here or the even better test kit from tftestkits here .


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