Watermom - Great article. I did have a high CYA last year 100+. I did 3 partial drain and refills to get it down to current levels of about 70.

As far as my CC levels, I am taking 30 part tap water to 1 part pool water. I come up with a range of .5 to 2 on the scale of both my test kits. I then multiply by 31. Last night, I put cl levels up to 60+ this morning it was about 40. I am going to test right now.

I'm pretty sure my black spots are algae. Two weeks ago, I had trouble brushing them away (would not move). Now, it appears to be dead and are easily brushed off. The are mostly on the corners, and around my underwater pool light. It seams to like to form there but it does also sometimes form on bottom. I haven't touched it with my hand recently, but a few weeks ago it did not feel slimy to the touch and would not scrub off easily. Like I said, the pool is very clear, rarely used, 0 times since last Wednesday. Next week school is out and it will get much more use. Thanks, I will post complete set of numbers in an hour.