I had a whole bunch (technical term there) of dead algae too small to get caught by the filter. I was using a sock due to earlier problems with long, thing seed pods which blocked the pump basket.
I used the blue clarifying stuff )which turns the algae into floating bits large enough for the filter.
It worked quite well - the next morning, I heard the pump straining - the sock had become nearly completely clogged with the floating stuff.
Lesson: If you're going to use the clarifying stuff, either remove the sock or watch it like the proverbial raptor.
I tried (cheap) knee-high hose it snagged and tore on the roughness of the basket, and trying to extract one of the seed pods caused a hole the sixe of a quarter.
The last of the stockings is n ow the repkacement mesh for leaf skimmer