I have the biofilter in the falls. According to the instructions, I shouldn't do anything with that for a year, at least. In the skimmer, I have a pre-filter to catch all the doo-dads and little things that don't stay in the skimmer basket. Since the little oak pollen doodles and things like that will tend to clog the pre-filter pad, I do take that out and blast it with the garden hose on the "jet" setting. It's the only way to get it even "sorta" clean, since the filter pad fibers catch and hold everything. On the one hand, I probably am hosing off some good stuff -- but there is more good stuff in the media in the waterfall. And if I didn't do it, it would affect the way my pump works.