Pool has gone from Acidic to Basic - why?

jgold723

Active member
Jul 5, 2016
38
Biddeford, Maine
My pool used to run consistently on the acidic end of the pH scale -- 7.2 to 7.4. I was using the trichlor hockey pucks for chlorine.

I switched to liquid chlorine a little over a year ago to reduce the CYA levels (it worked).

However, now the pool runs consistently basic, around 7.8. I periodically add muriatic acid to bring that down, but it keeps going up.

Nothing else in my pool care methods have changed. Is it the chlorine? Is there a better way to balance the pH than what I'm doing?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,380
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
The trichlor hockey pucks are very acidic. So they were adding acid to your water constantly.

Sounds like your pH is pretty stable with only occasional additions of acid. All is good.
 

SunnyP2000

Bronze Supporter
LifeTime Supporter
Jul 8, 2013
237
Long Island, NY
Pool Size
17280
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite Pro (T-15)
My pool used to run consistently on the acidic end of the pH scale -- 7.2 to 7.4. I was using the trichlor hockey pucks for chlorine.

I switched to liquid chlorine a little over a year ago to reduce the CYA levels (it worked).

However, now the pool runs consistently basic, around 7.8. I periodically add muriatic acid to bring that down, but it keeps going up.

Nothing else in my pool care methods have changed. Is it the chlorine? Is there a better way to balance the pH than what I'm doing?
i dont have the answer but following. my PH is always around 7.8 and just wondering why? just like you i would add little acid to bring it down to 7.5 but it goes right up. btw i dont use pucks.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
18,608
Tucson, AZ
Pool Size
16000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Any body of water with carbonate alkalinity in it (which is pretty much all of the water on the surface of the Earth) will always have rising pH. Dissolved carbonates cause pH rise through the process of CO2 exchange with the atmosphere (known as CO2 outgassing). Your water was only “acidic” because the trichlor pucks were constantly adding acid to the pool. Liquid chlorine is effectively pH neutral when added to a pool so the release of CO2 from the water is what is driving your pH up.
 

cledee

Gold Supporter
Bronze Supporter
Jun 23, 2020
166
Concord, NH
Pool Size
18000
Surface
Vinyl
Chlorine
Liquid Chlorine
Pools with SWG probably have more issues with rising PH than pools with non SWG. But the main key with rising PH is alkalinity. So if you keep your alkalinity within the recommended ranges your PH shouldn't rise as much. So far this year my PH has stayed between 7.5-7.6, compared to last year when I had to constantly add acid to drop the PH from 8.0 to 7.2. The main difference is last year my alkalinity was 115 to start, compared to this year my alkalinity was at 50 to start.
 
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