Thanks everyone, I am just lucky that I have such a understanding fincee that loves fish as much as I do and put up with the mess for a year building it.
Well the big tank is 11',5" long by 6' wide and 4' deep. I use Blue max to seal the wood and the reasonI angled the inside corners was due to the blue max has a peel and stick seem tape and wanted rounder corner cause I thought it would be easyer to blend and round out the corner, to make it look nicer. I just nailed them in with finishing nails. All the wood was sprayed with an expoy sealer before I applied the blue max, my thought were kind of like a secondary barrier if the blue max were to fail some how. I probably would not go this route again, the blue max is a good product but I would recomnd it more for sealing up over concrete opposed to sealing over plywood. The discus tank that also built 6 years ago, I did in epoxy resin and that tank it just feels stronger and more forgiving if i was to drop a rock in it or scratch it some how, were the blue max did tare once moving those trees in and I had a lengthy setback repairing it. Now I did save a lot of money going the blue max route vs the epoxy, epoxy would have been more that double the cost to go that way. I am sure time will tell if saving some bucks was ok but the next one i build just for the piece of mind I will go epoxy.
The thickness of plywood was a 3/8 layer ontop of 3/4 plywood and all my framing was 12" center 2"x6"