Hi Tandy, I built a filter for my 50 gal that's in the house. It's 2 parts.....there are 2 tubs, one sitting on top of the other.

The water from the fish tank flows into the 1st (top one), which is where (most of) the solids settle. The top one, has a stand pipe that penetrates the top of the bottom tub.

The water flows to the bottom of the lower tub and flows 'up'. I have a small pump that sits on top of the bio-material. Of course, it pumps the water back to the fish tank.

I just siphon off the solids every day (or two) from the top tub...and I disassemble and rinse the whole thing out, about every 2 weeks.

I keep duckweed in the top tub....helps with the nutes. Plus, it's a handy treat to toss to the breeders.

I'll try to post a few pictures tomorrow. I need to clean it out anyway.