Constant High PH

Jun 28, 2014
41
Southern California
Pool Size
20000
Surface
Plaster
Chlorine
Liquid Chlorine
Hello,

I have a 20k gallon in ground gunite pool from 2006. I purchased the house about 8 months ago and drained the pool as the CYA was so high I couldn't even chart it. Everything has been going great except I am constantly battling high PH. I have tried to dose with 1 quart of acid every other day and it drops it down for a few days but then again about a week later I am right back up on PH. I have also tried larger doses with the same result. Is there anything I can do that I am missing? I am using Hasa liquid Chlorine and Hasa 31.45% acid.
  • FC 2.5
  • PH 8.0
  • TA 140
  • CH 220
  • CYA 20
  • Water Temp 78 degrees
  • 2HP pump that I run for 5 hours per day
 
Do you have any water features? How often are you in the pool? I think you are saying you manually chlorinate with liquid chlorine? A quart every other day is not a super lot. I use about a gallon/week in the swim season to keep my pH down.
 
What is the pH / TA of your fill water? Do you have an auto-filler? Do you know how much water you're adding due to evaporation?
 
Do you have any water features? How often are you in the pool? I think you are saying you manually chlorinate with liquid chlorine? A quart every other day is not a super lot. I use about a gallon/week in the swim season to keep my pH down.
I have a spillway that I am turning on for 30 minutes per day to chlorinate the spa. We haven't used the pool much yet but with summer coming we will probably use it 1-2x/week. Good to know, so it's normal to use this amount.
 
Your high TA is likely what is causing the pH rise. Your pool TA is about the same as your fill water. I suspect you are reducing it as you bring the pH down, but then refilling the evaporated water is bringing the TA back up.

Do you have a solar cover? It would help slow evaporation, and that in turn would reduce the TA rise from evaporation -> filling. Otherwise, you can try to force TA down by aerating to raise pH, then acid to lower TA and pH together, but that just means you're putting a bunch of acid in in succession instead of over time.
 
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