Why does my pH creep up.

vanessadickson · Jul 17, 2015

Posting this summers readings below. Can anyone tell me why my pH keeps creeping up. Dropping acid (love saying that, but its the legal way) every other week to deal with it, but if theres a cause I can prevent would like to know. Thanks guys! PS-before anyone asks, yes I use all TFP chems to test, no test strips or pool stores ?

Date Chlorine PH TAlk CYA Salt -Action Taken
5/25/15 -Opened pool
5/27/15 3.0 7.4 85 55 1800 -Added 400 lbs salt, 5 lbs. CYA
5/28/15 2000 -Added 200lbs salt, 4 g. chlor, chlor not working -low salt
5/30/15 7.0 7.5 90 80 3600 -chlorinator working at 60%
5/31/15 6.5 7.6 90 75 3600 -turned chlorinator down to 50%
6/3/15 8.0 7.8 -added 16oz. muriatic 31.45
6/6/15 4.5 7.65 90 65 3750
6/12/15 0.0 -SWG off 3 days(oops) added 384oz12.5%chlor,SWG45%
6/13/15 9.0 7.8 85 60 3800 -added 24 oz mur acid and 48 oz CYI
7.5. 85 -hot day, hi use, SWG @70%, added 3in. water
6/15/15 5.5 7.5 85 70
6/18/15 7.5 7.6 85 3700
6/21/15 7.0 7.6 90 -added two inches water and rained two inches
6/22/15 4.5 7.6 90 65 3200
6/24/15 3.0 7.7 95 - added 1 gal. of 12.5% chlor., 24oz. 31.45% mur. acid
6/25/15 5.5 7.6 90 65
7/1/15 11.0 7.8 100 -turned swg to 50%, added 16oz. of 31.4% mur. acid
7/3/15 13.0 7.8 95 60 -added 40 oz. CYA,
7/4/15 12.0 7.7 95 -added 32 oz. 31.45% mur. acid, turned SWG to 35%
7/7/15 10.5 7.6 95 60
7/17/15 4.5 7.8 95 60 3100 -hot days, added 32 oz mur acid, swg up to 40%

Any and all suggestions appreciated! -PS TFP saved me from bull-dozing my pool a couple years ago ?

Texas Splash · Jul 17, 2015

Well, the only thing that comes to mind is the TA. I know many pool builders and manufactures stress the 70-120 range, but I've had more success letting the TA comes down a bit. TA helps to buffer the PH, therefore they seem to run together. If the TA is high, the PH will creep-up. My TA is currently anywhere from 60-70, and my PH never budges. I'm not saying to do anything too drastic in adjustments, but perhaps a little lowering of the TA, slightly each time, to see how that works on the PH.

Also, do you have anything generating aeration? Aeration also increase PH. Just a thought.

woodyp · Jul 17, 2015

Salt Water Generators drive up PH all on their own.

vanessadickson · Jul 17, 2015

Thx Txsplash, makes sense but dont have any fountains or waterfalls that generate aeration, maybe the excessive rain we have had?? Woodyp thanks! I know that about SWGs but Im trying to understand the why of that--call me crazy or just inquisitive, want to figure out if I can implement some sort of regime that avoids creep.

Texas Splash · Jul 17, 2015

You might like this thread: Why does aeration cause an increase in ph?

Gets a little deeper.

lefty51 · Jul 17, 2015

This may not be the answer you want, but.......as woody says our SWCGs' generate bubbles that help PH rise. My solution was to get TA and PH right, THEN added borates. Now my PH is stuck at 7.7.

And the water looks mavvuuuulous

chiefwej · Jul 17, 2015

You are using considerably less MA than I have to use, and your pool in nearly twice the volume. SWG causes pH rise. Any aeration you have will also cause it to rise. Lower TA will help buffer. Adding borates will also help buffer. You can do both and it will slow it considerably, but if your pool is like mine, you will still have a constantly rising pH. I think it's just part of the cost of using a SWG.

chem geek · Jul 17, 2015

Lowering the TA and having a higher pH target will help reduce the amount of carbon dioxide outgassing. Using 50 ppm Borates would extend the time between acid additions though the total amount of acid needed will be roughly the same.

If you have short pipe runs from your SWCG to the pool, then there can also be some undissolved chlorine gas outgassing in which case that is not helped by lowering TA or raising pH. It may be helped by pointing returns (especially the closest one to the SWCG) slightly downward.