Building this for my snapping turtle, it will be 300 gallons when finished. I am going to incorporate a top on it as a basking area. I have him in a 75 right now and 2 weeks ago did my first run with a diy wet dry trickle filter which is what I think I am going to do with the plywood tank. Going to use half inch glass, fiberglass in all corners, then pond shield over plywood. Might try my hand at a 3d background as well. I did have a thought on a bottom and wondering what others opinions are, why not do a 3d on bottom as well? It would save the pond shield from scratches from substrate, be easier to clean, only thing I can see that might be bad would be seeing the poops on bottom, but that's as easy as a net lol.