Thanks for the responses everyone. Now I'll know what to do if I ever really have that bacteria problem . Here's my latest tale of woe.

Thankfully, I realized what was going on the day after I last posted. I had my chlorine up to 22 and before I went to work the next morning I tested it again and it was holding strong. After work the chlorine was down to 9. Pretty fishy, huh?

My pool was built in the fall and opened late last year. The pool store that my builder turned me over to told me everything I needed to do to get the pool going. That included dumping in a bunch of di-chlor to shock and tri-chlor for regular chlorination. After just a 2 or 3 weeks they were measuring my CYA level at 100. I now know that it's implausible for the CYA to rise that fast without specifically adding CYA to the water, but I had no idea at the time.

I have Ben's test kit now and the results I published earlier were based on my testing, with the exception of CYA. I've been getting comfortable with the kit but hadn't yet added the CYA test to my repertoire, so I relied on my old friends at the pool store (they measured 50). After I saw what was going on with the chlorine I did the CYA test myself and found no measurable CYA. I went to another pool store and they confirmed this (although they measured a PH of 8.0, when I knew it was really 7.4 ). I don't know why they are so off on their CYA test, but at least they're consistent!

I've added CYA. I thought that I could use the pool stores once in a while just to confirm my test results, but I'm done with them. From what I've seen, test strips are a pillar of accuracy compared to the pool store.

Lenny