We had a pouring rain all day on Monday. The water level in the pool got up to the top of the skimmer. On Tuesday evening I tested the water and this is what I got:
CYA- 20 ish (black dot did not completely disappear)
I raised the CL to 3ppm. Didn't get a chance to lower the water level. Yesterday evening I was able to get out there and test and vacuum. My test results were:
CYA- still 20 ish
There were some green patches on the bottom. I vacuumed to waste ( the tip for doing it with cartridge filters works like a charm!) and got the loose algae up and water level down some. I noticed that the liner is now bleached up to where the water was at the top of the skimmer. I added a gallon of 12.5% to shock it and did some brushing. This morning when I tested the CL it was:
Any idea what is bleaching the liner? I know the CYA is still low and the pH is at the lower end of the range, but I thought it was high enough to prevent bleaching.