How Long Does It Take To Raise Ph Using Aeration?

[Gavin]

I have a fountain type jets that shoot up and down into the pool that I'm using to raise the pH. I dropped TA down to 80 and pH went down as well to 7.0 so that's why I'm aerating.

how long will it take to raise pH to at least 7.2? Thanks. I was thinking about leaving system on for 4 hours tonight to try and raise pH to 7.2

[chem geek]

It's hard to say, but I know that if I just turn up all of my returns then overnight the pH will rise from 7.0 to at least 7.2 and sometimes 7.4 -- at least when the TA is around 100-140 ppm. As the TA gets lower, the pH rises more slowly even with aeration.

[Gavin]

It's hard to say, but I know that if I just turn up all of my returns then overnight the pH will rise from 7.0 to at least 7.2 and sometimes 7.4 -- at least when the TA is around 100-140 ppm. As the TA gets lower, the pH rises more slowly even with aeration.

cool thanks Chem. I'll check to see where pH is in the morning.

[chem geek]

Just wanted to say that the only time I have had the pH that low at 7.0 was when intentionally trying to lower the TA which is why I had the returns pointed up and the pump on high. It's been a while, though. My pool water chemistry is awfully stable.

[Gavin]

Just wanted to say that the only time I have had the pH that low at 7.0 was when intentionally trying to lower the TA which is why I had the returns pointed up and the pump on high. It's been a while, though. My pool water chemistry is awfully stable.

this is what I'm trying to do with this SWG. It has a fountain and I'm using that to aerate.

but I don't want the actual alkalinity to be to low.

If I get TA down to 70 won't that make the actual Alkalinity very low? If CYA is 80? Isn't 1/3 of the CYA part of the TA?

That would make the actual alkalinity only like 47ppm?

[chem geek]

You are correct that at a pH of 7.5 about 1/3rd of the CYA is part of TA. If you need the TA that low to slow down the rate of pH rise, then that's perfectly fine. You'd just increase the Calcium Hardness (CH) and your pH target (say, to 7.7) to compensate the saturation index you can calculate with The Pool Calculator. You can also add 50 ppm Borates to the pool to help slow down the rate of pH rise, not only by the additional pH buffering but also by the algae inhibition properties of the Borates which may lower chlorine consumption letting you turn down your SWG on-time somewhat.

[Gavin]

You are correct that at a pH of 7.5 about 1/3rd of the CYA is part of TA. If you need the TA that low to slow down the rate of pH rise, then that's perfectly fine. You'd just increase the Calcium Hardness (CH) and your pH target (say, to 7.7) to compensate the saturation index you can calculate with The Pool Calculator. You can also add 50 ppm Borates to the pool to help slow down the rate of pH rise, not only by the additional pH buffering but also by the algae inhibition properties of the Borates which may lower chlorine consumption letting you turn down your SWG on-time somewhat.

Thanks chem.