Why would my TA crash?

[waterbear]

If you have algae in the water then your water will be cloudy, not clear. Since the CYA test is a turbidity test the extra cloudiness from the algae will give a false high reading on the CYA so if you CYA is testing the same it very possibly is lower than it was. Wait for the pool to clear and then retest your CYA.

[JohnT]

If you have algae in the water then your water will be cloudy, not clear. Since the CYA test is a turbidity test the extra cloudiness from the algae will give a false high reading on the CYA so if you CYA is testing the same it very possibly is lower than it was. Wait for the pool to clear and then retest your CYA.

I'd kind of filed that as a possibility to give me an artificially high CYA reading, which I had expected to be in the 20ppm range. Still in shock over the alkalinity drop. Fortunately I have a ready source of alkalinity increaser in my fill water. Maybe for one season I'll be able to vacuum and backwash like a normal person.

[TwistyKat]

Just thought I'd post a note regarding my progress.

In hindsight I think the reagents might have been faulty to some degree, because after adding all the baking soda that I did (I panicked!) it took two and a half gallons of muriatic acid added over two weeks time to bring the TA down to 100.

TA never went higher than 190 but it took a while before the number started dropping. Early in the treatment the MA had almost no effect on the TA.

After the PH came down I started aerating with a small submersible pump in the corner of the pool and the PH never went below 7.0.

So right now I'm sitting comfortably with TA at 100 and PH at 7.2 for my 32K
gallon gunite. I shocked again and covered it back up. I should be opening for the season in two or three weeks from now.

So all's well that end well.