Thats a very good question And I couldnt believe it with my own eyes, but it was definitely clear (you could even see the main drain in the deep end). Maybe we had so much extra rain water that it caused enough dilution to remain clear? Dunno. We did have an awful lot of rain in April.

I suppose what was on the bottom could have been some sediment, but it was coming out green and slimy whatever it was, and there was a lot of it. I just assumed algae because it looked like a dark green. Shocked the pool for about 2 days, vacuumed to waste and 90% of it went away, I brushed the rest towards the main drain (aka "lazy mans vacuum") and am waiting for the water to completely clear up again (just a little cloudy towards the deep end, clear in the rest of the pool). All in all took 4 days from open to swimmable. Id like to see it down to 2, because Im lazy that way