Been awhile, but I'm back...

[SunnyOptimism]

Since adjusting my TA down a bit (about 80) a couple years ago I haven't had to add any acid at all.

Hey JimK!

I think for us it's the difference between vinyl and plaster. Vinyl pools tend to have pH drifts that are acidic whereas plaster pools drift alkaline. Therefore the alkaline drift caused by an SWCG can be balanced by the acidic drift in vinyl. For plaster that typically drifts alkaline, it's a compounding problem. I also get a lot of alkaline drift due to my rock waterfall and spa spillway running so it adds to the acid demand.

But I do agree that it helps to be on the lower side for TA to make the acid additions more reasonable. I also added 50ppm borates which helped to slow the pH rise but that also creates the need for larger acid additions to lower the pH. My pH is manageable but I just wanted to throw out the idea that SWCG's are not cost-free in terms of water balance.

[JimK]

Hey JimK!

I think for us it's the difference between vinyl and plaster. Vinyl pools tend to have pH drifts that are acidic whereas plaster pools drift alkaline. Therefore the alkaline drift caused by an SWCG can be balanced by the acidic drift in vinyl. For plaster that typically drifts alkaline, it's a compounding problem. I also get a lot of alkaline drift due to my rock waterfall and spa spillway running so it adds to the acid demand.

But I do agree that it helps to be on the lower side for TA to make the acid additions more reasonable. I also added 50ppm borates which helped to slow the pH rise but that also creates the need for larger acid additions to lower the pH. My pH is manageable but I just wanted to throw out the idea that SWCG's are not cost-free in terms of water balance.

Interesting stuff. Thanks for the clarification.

[steveinaz]

With my SWCG I typically had to add about 3/4 cup of muriatic each Saturday. This was for a 13k gallon/plaster pool with waterfall. No biggie.

[SunnyOptimism]

With my SWCG I typically had to add about 3/4 cup of muriatic each Saturday. This was for a 13k gallon/plaster pool with waterfall. No biggie.

My spillway runs a lot so my acid demand is quite a bit higher than that. I probably add about 2-4 oz of MA per day to my 16,000 gal pool. That's if I want to keep it at 7.5/7.6 but I typically let it drift up a little higher than that. Someday I'll procure for myself an IntelliPH and then I can more consistently add acid.