After a week of cool weather pulled the solar cover off 20' AG and saw a "dirt" ring around the outer edge on the bottom of pool. Tried to vacuum it up but it was too fine. Chemicals all tested within good ranges that day. After a couple of days of the kids playing and stirring up the water now the entire pool looks green and there is a light brown dust on the bottom everywhere.
I backwashed the sand filter thinking because the pressure gauge was slightly in the yellow range. Lots of brown water came out. Ran the filter again that night, water is the same color and the dust/dirt is still there.
Tested again today:
Not sure what to do now or exactly what this stuff is. We had rain a couple of times over that cool week so I was thinking it was just fine dirt/pollen but now the whole pool looks green. The lowest my FC has gotten since discovering the "dust" has been 1.5 and I bumped it back up to 4/5 right away.