you can buy bottle brushes on flexible wire, similar to a pipe snake used by a plumber for your toilet. most are rated to 3/4 to 1" diameter pipes. these are designed specifically to clean around corners like in j-tubes on overflows. feel free to shoot me an email if you cant find one and i can send you to a place that carries them.
also, anything clear can be painted white or black to keep light from entering, this will keep algae from growing.
i break down my pump and clean it every 6 months.
krux@lanset.com