I built this twenty years ago based on an etching in one of my son's insect books. It was made using mostly salvaged materials and including the pump cost about $100. The wood is mahogany and I carved the legs myself. When I last had it running, I used an under-gravel filter system plumbed through the floor with an external sealed filter (homemade) and pump which were housed in a box attached to the underside of the epoxy coated ply-wood floor. The water retuned to the tank through the middle of the floor and an inverted drilled-out tree stump/root, which provided a land area for critters and plants in addtion to a very nice waterfall. Over the years I've had just about everything in it including fish, frogs, crayfish, water snakes, turtles, dragonflys and salamanders- I even considered bats. All were species native to my local area. Lately it has been a glorified terrarium. So, I'd like to modify the filter system to something a bit more modern/efficient and keep it through the floor. Any suggestions? I'd like to keep things as hidden as possible.