Chasing pH

DanL

Active member
Nov 23, 2016
35
Las Vegas NV
After finding this site, took over pool care myself. Changed water 3 weeks ago, and dialed the water chemistry right in using info from this forum and Pool Math.
One issue...I have to keep adding acid to keep pH down to just 7.5. Have targeted 7.3, but have not gotten there even though seeming to be adding a lot of acid.
Details:
Pool unused now. In-ground cement. Covered with blanket. Water temp mid 70's. Filtration run 4hrs/day with waterfall spa overflow. Water very clear, no algae, etc.
Typical values last 3 weeks: pH=7.5-7.6, Cl=5+, CH=450, TA=110, CYA=50, FC=5, CC=0, TC=5.

Chlorine has held pretty constant...only 4qts of 8-10% added over last 3 weeks (after the initial dosing)
CH is high, but that is from the city water source here.

Have been using KleenStrip muriatic acid. Best estimate from web MSDS is that it is 20% acid.
Have added 6 qts of acid over last 3 weeks. Additions usually bring pH to about 7.4 (I use Pool Math to target 7.3), but a day or two later, pH is up to 7.5+ again.

Am I just not adding enough acid? For an unused pool with pretty stable chemistry, does the rate or acid use seem out of line? Is the aeration a contributor to increasing pH issue as some posts indicate?

As always, thanks much.
 

pooldv

Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
Aug 10, 2012
25,178
FL panhandle
I would let your ph sit at 7.8 and lower it to 7.6 when it gets to 8.0. The spa overflow is driving pH up through aeration. If you run it less the pH will go up less. Also, TA at 110 will push PH up. Adding acid to lower PH will slowly lower TA too. Or you can actively lower TA following this, Pool School - Lower Total Alkalinity. TA down between 70-80 will slow your pH rise quite a bit.
 

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