CSI vs. pH

[steveoFresno]

Hi all,

As the weather and my pool water gets colder, it’s becomming harder to keep both the pH and CSI in range. My question is this: I understand that pH can affect swimmer (eye) comfort; but, during the winter when no one will be swimming, does the pH matter independently or only to the extent that it affects CSI?

Here are some current numbers:
FC- 6
CC- 0
pH- 8
TA- 70
CH- 300
CYA- 50
Salt- 3000 (no generator)
Borates- 0
Temp- 70°F
CSI- -0.08

In this example, the pH is a bit high, but the CSI perfect. Should I bother lowering the pH, or let it ride high over the winter as long as the CSI is neutral?

Thanks in advance!

 

[JamesW]

I would lower the pH to 7.9. Are you sure that it's at 8.0?

 

[steveoFresno]

It’s a bit subjective with colorimetric pH testing. It looks like 8 to me, but I wouldn’t bet my life on it. Out of curiosity, in what way would 7.9 be better than 8.0?

 

[JamesW]

The problem with a pH of 8.0 is that it's too close to the end of the test range. That makes it unreliable.

During the winter, the ph can increase quite a bit from the plaster and you can get scale.

In my opinion, once you hit a pH of 8.0, the risk of a runaway ph spike increases as well as the likelihood that you will get scaling.