Dropping TA, for the workin man or woman....

Dan
I don't know about your fill water, but here in Sierra Vista the fill water TA is 170ppm--I'm sure this contributes to the rising pH problem around here. All of our friends with pools also battle rising pH on a constant basis.

I just checked, the fill water TA is 90, and the CH is 80.

When I first started testing my water, about 4 weeks ago, the TA was low, don't remember how low, but it was lower than the recommended 80-120 for concrete/plaster, so I added enough baking soda to bring it up to 100. The next test was at 90, and yesterday it was at 80. So if alkalinity is dropping, acidity should be rising, which means pH should be going down rather than up, right? And yet it goes up. There must be something wrong in my reasoning here, hopefully the experts can straighten me out.

Clearly, though, I have an issue with the TA dropping, which must mean I have some unwanted aeration going on. I never use the waterfall, the returns are down or sideways and never break the surface, about two weeks ago I disconnected the ozonator which I determined was a suction side device and PoolDoc suggested could be aerating, the only thing left that I can think of is my in-floor popups, which when I use them, definitely ripples the surface a lot in the shallow end. Until a couple weeks ago I was running that every night, but I've stopped that practice just to see what effect it would have on the cleanliness of the pool, and to conserve electricity. So I think I'll add some more baking soda and keep testing to see if that makes a difference, and just use the popups when the floor is actually dirty!

You are most definitely going to need to get your Calcium Hardness (CH) higher. You can use The Pool Calculator to calculate the saturation index which you want closer to zero. If it's too negative, then your pool surface will have a tendency to dissolve into the water; if it's too positive, then there will be a tendency for scaling to occur.

Yeah, I've already done that, I was just reporting the fill water numbers. Currently the pool is at 190.

Dan