I'm sure this has been done before, but I thought i'd share my story. I setup my 220 around 4 months ago, and after I got the sump setup and plumbed and got the tank filled I threw in some rosies to help speed up the cycle process. I Also used old sponges and such. Well once I moved my cichlids from my 75 to my 220 after 2 weeks or so, they made short work of the 24 rosies...or so I thought. I was messing around in my sump today (a 55 gallon tank) and i noticed something odd. 1 rosie was swimming around, happy as can be. This might not sound that crazy to start with but this means he got through the slots in my overflow box (crazy skinny slots) down my standpipe (not to suprising) Through my filter floss (some slight gaps cause i'm paranoid of clogs and overflows) through my drip tray (I have no idea how) wiggled through my bioballs (10 or 15 gallons worth, half submerged, half for wet/dry) and now resides on the back side of my bubble trap. To top all this off I have had a 3" crayfish in my sump since about a week after I moved the fish over. How he wiggled through this gontlet I will never now. But I figured he deserves to live out his life safely in my sump, And now i feed him regularly.
Crazy, huh?
Crazy, huh?