I have checked my levels with strips and showing basic normal levels except FC is low. Leslies said 1000 phosphates, slightly high PH and low FC so I dumped 8 bottles of bleach and my last lb of shock. Now FC is only 2-3ppm and stains still there. The dark brown spots are nickel to dime size and come off with a pumice scrubbing. Black algae? My other concern is those brown faded stains. They are on the walls and the floor and I thought maybe the high PH. Suggestions?