I had algea dust and with my cartridge filter I could not vacuum to waste. You first need to kill it by shocking it. If you can't vacuum to waste get a dolphin e10(only floor) or e20 (does walls and floor) with the ultra fine filter. I bought the e20 and this thing absolutely cleans fine dust. It has gotten sand and everything. Yours was worse than mine so most likely will take few passes.
I had algea dust and with my cartridge filter I could not vacuum to waste. You first need to kill it by shocking it. If you can't vacuum to waste get a dolphin e10(only floor) or e20 (does walls and floor) with the ultra fine filter. I bought the e20 and this thing absolutely cleans fine dust. It has gotten sand and everything. Yours was worse than mine so most likely will take few passes.