how to stop the bubbles

[isz]

i just picked up a slightly used HOB skimmer, and i can't seem to keep the either the bubbles out of the tank or the water off the floor. i tried using a prefilter, but that worked for about .5 an hour, so i stuffed more prefilter in and around the return line. i watched that setup for about 20 minutes, decided it was good, only to have my roommate yelling at me for spilling MORE water on the floor. is there some other sort of media that i should be using? if not any other ideas?

 

[cap'n pete]

Shoving media into the return, as you found out, creates too much back pressure resulting in the water seeking a path of least resistance (over the media and onto the floor)! The skimmer may just need to break in, let it run for a few days and see if the bubbles in the return subside. It may need adjusted. Does it allow you to adjust the amount of air or water? Do some tweaking and see if that helps.
The only other thing I could suggest is if none of those things work you could build a bubble catcher. Basically a plastic box suction cupped onto the back of the tank. Positioned so the return flow spills into it. You fill the box with sponge media and drill lots of holes onto the bottom half for the water to go out. the bubbles should get caught in the sponge. HTH