Water looks pretty darn good compared to last week when I opened it to a bunch of gray sludge resting on the bottom. Is this what one would call mustard algae? I vac'd most all of it out and the filter caught most of what got suspended. Just a bit more vac'ing to do today. Should I add more chlorine to get my CC to zero? Also, after much reading in pool school I couldn't find a chlorine level where it would be safe to put down the solar blanket. Any ballpark figures out there? We're finally suppossed to get some heat & sun out here & I'd like to be able to put the solar cover down at night. Thanks all & have a good weekend!