Im planning on building a 240 gallon tank from the 240 gallon pond I have now. The liner in the frame sprung a leak. The frame is made from 2x12's. Would it be ok just to line the frame with 1/4 inch plywood and then epoxy it? Or do I need to go with 1/2 inch plywood. I plan to use 1/4 inch tempered glass for the 20 by 40 inch window.