My skimmer was overflowing continuously for quite awhile in the beginning as well. Now that it has been running and built up some slime it works great. I only have 1 clown in the tank right now so there isn't much it's pulling out. I have my middle compartment filled with marco rubble and my temp probe/return in the right. I don't have a heater in mine since my condo never goes below 75. I did build a custom top out of 1/4" clear mesh and a screen frame to combat jumpers because the glass was causing heat issues with the MH. The only thing I have left to find is a check valve for the return line so when I do water changes the water doesn't flood the back compartments