I no longer culture phytoplanktons but here is a shot of therotifer vessels.
They work really nice for cleaning.. While they are still full (rotifers and culture water), I remove the air bubbler, wipe the sides, swirl the water to get a good vortex going and the stuff that I wiped off of the sides circling in the center, let it settle for a few.. Then a quick flush (open/close)with the ball valve to let the gunk out before I harvest. Then to harvest, I put me seive under the valve and open the valve. I usually havrvest 1/2 per day, top off with new water and feed them phyto.