Waterbear,
I have to go to a nursery meeting at church tonight, but I definitely want to do this! Like you, I don't think this is what's going on, but (like you) it's a nagging thought now in the back of my mind that I'd like to rule out.
I have to work for a couple of hours tomorrow morning (ebay business), but I will tackle this test and report back to you either late tonight or tomorrow afternoon.
I agree that this needs to be addressed, even if it is not the culprit!

By the way, I had a little GOTCHA moment earlier that made me realize how impatient I am acting... I walked out to my pool, frustrated, about an hour ago and the algae is CONSIDERABLY BETTER! I mean, a good 1/3 of it is gone!
Guess I'll quit whining now.