How long has it been setup? What's your filtration? How much are you feeding? Lighting? Water Change schedule? Give us a bit more info, and i'm sure we'll figure it out for you.
I've run into this several times on W/D sump systems thats why I always recomend either a sealed pressure system or an additional power filter for mechanical filtration. you can also try using a 25 mic. bag on the overflow terminus.
been set up for bout a month... feed only 2-3 bloodworm cubes a day only have two baby dats and the pink tails in there. ive only had fish in there for a week or so. and ive changed the water twice i think.
so i should put a filter bag deal in the sump to filter debris and stuff?