The local fish club is having a sponge filter workshop at their July meeting. Any ideas for the best designs you've made. I have seen a number of methods using lift tubes, ceramic tile or glass bases, and other materials. My favorite is probably a 4" by 4" y 12" sponge with a hole drilled a little more than halfway down from one end. it can be used with an airlift in a deeper tank, or flat with a power filter.