Hi all, I've been banging my head around the internet and decided to ask the experts here for some advice. I want to make a 10x4x4 heated pond from 2x4 or 2x6 frame with studs and a framed in 3/4" 48"x24" acrylic window. It will be 10-12" in the ground so 36-38" above. I'm thinking the spacing of the studs would be 8-10" on center with a 3/4" plywood lined and epoxy coated and 3/4" plywood wrapped on the outside with a second 3/4" acrylic window on the outside to act as a double pane and strength. I can do this out of steel which I am more experienced in but want to have the space in between the studs for insulation and also steel I feel would stay cold compared to wood. Also steel is much more expensive than wood. Please let me know your thoughts and experiences if you have them, it would be much appreciated.