Makes sense.

As I think about it more, there was one day I let it drop to 3 ppm FC. With the CYA where it is (45), I suspect that's when it started. Grrr. I thought was going to have a trouble free summer.

But the good news is that the water was pretty clear this morning with a heavy yellowish layer on the bottom. I vacuumed it and swapped filters. It's green and cloudy again now, but that's just because my vacuuming stirred it up again. I'll let it settle down with the filter running and will vacuum again tomorrow. I'll hit it with another gallon of bleach tonight.

In one of your last posts, you recommended I get a cheap OTO kit. With the Taylor kit I already have, I wondered why. To keep me from using up all the expensive regent measuring the shock-level FC? Not a big deal; just trying to glean as much info as I can from this experience.

Anyway, thanks for everything.