I have been trying to get rid of whatever for a week now... I thought it was mustard algae as it looks like sand but puffs up when brushed... it is thicker in some places but always a thing coat all over the bottom and steps. I have SUPER shocked it, brushed it many times, did two waste vacuums and it's better but still showing up and the water is very very cloudy???? Please HELP, I have company coming next week????