Hey guys, my father is a welder and I'm just kinda wondering why people never do metal tanks..? Instead of plywood and a 2x4 frame, couldn't a metal frame with sheet metal sides work? And wouldn't it be less susceptible to leaks and more sturdy? It would be water tight before the pond sealer stuff even went in... With all of the seams being welded. Wouldn't it also be cheaper to do?