PoolDoc,

You were right regarding the pool service company - they seem to be more than forthcoming with information and pretty straight up.
They said at the end of the season CYA reading was down to 18 and they didn't want to bump it until needed in the spring.

Also some good news on my shock treatment. Immediately after I shocked in the evening, TC was 10+, but FC didn't read at all, so I presume the strips are defective in at least this regard. In the morning TC was still at 10+.

The test strip first indicator for CYA is at 50. So tabulating all of this I assume that I do not have a problem with eaten CYA, only some normal pool opening (I guess?) green algae.

Also in the morning the water appeared clearer and lost some of the green tint. So I'll keep up with shocking until the pool is clear.

Thank you,
Vlad