AquaClears are easy to keep clean too, less mucking about than the canisters. I have an AquaClear 300 running on my 4ft, along with a large Eheim wet/dry unit. Like Ira, I think $20 sounds like a very small filter. I don't know the flow rates so don't know which AC does 570lph.
You need at least a 300 or 500 in the AquaClears. They have it written on them starting with the mini then I think they go up as 200, 300, 500 but don't know if this refers to lph.