Hi....I have built a DIy wet/dry filter out of a plastic 3-drawer set(TARGET).......The sump is a 55g plastic storage container.......Get the idea.........lol........It works fine for my 125g........The top drawer is where the water first enters.......There is filter floss in there........I was thinking of putting some freshwater crabs in there to eat some of the debris that falls in........Anyone try this?????????