Sorry this is so long, but I figured more information was better.
On Thursday, I noticed some slight green blooming on the walls at the waterline and just below mostly all around my pool, around the return jets and Polaris connector, and on the "seats" under my waterfalls.
Friday I shocked to 15 FC per Pool School and Pool Calculator. Scrubbed that day with a brush (that was rough, as some of the algae was stubborn). Noticed that on the horizontal surfaces (steps, seats, etc.), when I brushed, clouds of grey would come up. Nothing was visible until I brushed (the surface is itself a grey color), but I could brush the grey stuff off into the deeper parts of the pool. So I did that.
On Saturday morning, FC was at 14, but there were still a few spots here or there that I had missed, so I rescrubbed and added chlorine. Again I had the big grey clouds when I brushed the steps, etc. I added a little too much chlorine this time, and FC went to 21.
Yesterday morning FC was 15, and I could find no green algae spots anywhere. But when I brushed the steps I got the clouds again. So I got concerned. I poured in enough bleach to get the pool to 25 FC. This morning the FC was 21, and I still have clouds when I brush the steps.
Is this algae or something else? The color of the stuff on the bottom is not discernible from my medium-grey pool bottom, but when I brush it looks like grey with a slight brown tinge. The particles are extremely fine - like if I had mixed water and mud until the mud was fully dissolved and then poured it into the pool. It will cloud the pool in the brushed spots for 5-10 minutes then clear up. Running the pump for 72 hours continuously made no difference.
Any thoughts on what I've got? Thanks in advance.