I have a re-occurring issue with algae forming on the bottom of my pool. The water stays clear but the bottom grows a thin layer over a few days. Recently slammed and cleaned ~20ppm chlorine for 4 days. ONCL dropped by 0.5 over 2 nights CC hovers at 0.5 sometimes 0. Any extra troubleshooting tips?
Chlorine source: Bleach (chlorine feeder not in use)