rising ph levels

[wolfcue]

Why does my ph keep rising?

Latest readings:
tc 2.5
fc 2.5
cc 0
cya 40
alk 150
ph 7.8

intex above ground 18x48

Yesterday all readings were the same except ph was 7.5

It took us a long time adding muractic acid and then aerating to get the alk down, but now the ph keeps rising. We will add acid and it will drop to 7.2 to 7.5, but a couple of days later it will be up to 8. What do I need to do?

[sevver]

I think that the alk is still a bit high, and also if you have kids who use the pool, then with splashing and all it will raise the Ph. Are you still aerating, that will raise the Ph also. I have found that adding acid to my pool around once a week is necessary as the Ph does seem to rise a bit, although slowly. If I am not mistaken the Alk needs to be at the highest 120, but I could be wrong.

[aquarium]

I'm still experimenting with this, so take that as a note of caution.

I lowered the alkalinity in our pool from 220ppm to 100ppm and still had the pH bounce back up to 7.6 each day after adding muriatic acid the day before to get it down to 7.2. So I lowered the alkalinity to 70-80ppm and now the pH is holding at 7.2 over the last two days. Be careful with the amount of acid added as you approach the lower alkalinity levels, a little has a bigger effect on the pH and it doesn't bounce back as far.

I'm not sure of the chemistry involved, but I suspect there's a CO2 interaction ocurring at the water surface/atmosphere interface that sets the pH dependent on the alkalinity.

[wolfcue]

The pool is vinyl lined and I thought my alk levels were okay for my pool. I stopped aerating after I got the alk down and there really hasn't been anyone in the pool. I guess you just have to keep adding acid to keep the ph down. Thanks for the help.

[wolfcue]

What does the check mark after my post mean? Just curious.

[SoCalBoo]

wolfcue - you don't have an swg by chance, do you?

[waterbear]

What does the check mark after my post mean? Just curious.

It means you are subscribed to the thread and you can check settings in your control panel to get email notifications of new posts in the thread.

[azimmer1]

Rising pH
Are you using the all bleach method? If you are, that may be why it is climbing.
Anything that you add to the pool, can change the pH depending on the pH of what you are adding.

Bleach, sodium hypochlorite, has a pH of around 10 or 11, very alkalotic, so the more you add, the higher your pH will go.
I have found that in my pool which is open all year round, I ONLY ADD 2 chemicals!!!!!!!!

Bleach and Acid.
Bleach for my source of chlorine and acid once in a while to bring the pH down.
That is it. Once your pool is "tuned" it can be that simple.