PH constantly increasing and can’t identify the reason

[zdez]

Hi everyone, I’ve been trying to figure out why my pools ph keeps reaching 8.0 monthly. I drop it to 7.4 every time. Here’s what I checked:

1. Salt water but salt chlorinater broken so it’s not causing ph to increase (I use liquid chlorine)
2. Plaster pool but more than two year old, and I’m only brushing every other week
3. I also have boric acid as ph buffer which does not help much (~30ppm)
4. Not using fountain (no aeration)
5, Alkalinity at 100

What else should I check to eliminate the issue? Now using one gallon of muriatic acid every three weeks. Thanks!

 

[Bperry]

Hi everyone, I’ve been trying to figure out why my pools ph keeps reaching 8.0 monthly. I drop it to 7.4 every time. Here’s what I checked:

1. Salt water but salt chlorinater broken so it’s not causing ph to increase (I use liquid chlorine)
2. Plaster pool but more than two year old, and I’m only brushing every other week
3. I also have boric acid as ph buffer which does not help much (~30ppm)
4. Not using fountain (no aeration)
5, Alkalinity at 100

What else should I check to eliminate the issue? Now using one gallon of muriatic acid every three weeks. Thanks!

pH naturally rises over time and high TA (over 60ppm) will make it rise faster. Aeration also makes pH rise.

If you let the pH rise to 8.0 and only reduce it to 7.8 it will also slow down as well as the TA lowers.

 

[Texas Splash]

What else should I check to eliminate the issue?

Agreed with Bperry. Let that TA come down. Each time you hit the pH with acid, lower it to a desired pH target of about 7.2 and that should also help to lower the TA. You can essentially allow the TA to fall in the 50-60 range with no issues. That should help.

See our Pool Care Basics for more info. Welcome to TFP!

 

[Mdragger88]

Hi everyone, I’ve been trying to figure out why my pools ph keeps reaching 8.0 monthly. I drop it to 7.4 every time. Here’s what I checked:

Your ph will constantly rise to some degree in a plaster pool - its just the nature of things especially if you have higher ta/ph fill water that you’re regularly adding. BTW You should be checking ph more than once a month. At least weekly & preferably multiple times per week if it moves alot.

1. Salt water but salt chlorinater broken so it’s not causing ph to increase (I use liquid chlorine)

Swcg’s do not cause ph to rise

2. Plaster pool but more than two year old, and I’m only brushing every other week

Still contributes to some degree & will probably do so indefinitely

3. I also have boric acid as ph buffer which does not help much (~30ppm)

30-50ppm is the recommended range for a helping hand from borates so increasing a tad may help but first work on your TA - more on that below….

4. Not using fountain (no aeration)

Although any splashing or movement aerates the water

5, Alkalinity at 100

This
You can Work on lowering TA to around 60 & you will find the rate of ph rise will lessen. You’ll want to do this before increasing borates further as the additional borates will mean more acid is required to achieve the same effect on ph/ta.
Here’s how to do this safely

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.

www.google.com

What else should I check to eliminate the issue? Now using one gallon of muriatic acid every three weeks. Thanks!

Check & record your fill water ta & ph so you understand what you’re working against.
That amount of 31.5% muriatic acid works out to an approx 0.5 drop in ph per week in your pool volume. This is really not an excessive amount.