I have a sponge filter in both my 125s to try them out, they are the hydro V so their big. I've had them in for a few weeks and they just don't seem to suck any debris in them. I watch things float right past them all the time and it just seems like the odd particle gets caught on it but not anything to make a difference. Really frustrated, I'm pretty sure I have them set up right. Here is some pictures. One is my oscar tank which I show debris that I left on purpose and just in case that debris is too big I have my other tank and as you can see its small stuff like left over blood worms.