Your basic concept looks reasonable, but I think using wood near the water line is asking for trouble. Wood fibers tends to swell and distort with changes in humidity.
++sigh++
But to be brutally honest, do you have any idea how much work it is to clean up water damage? It's a nightmare!
My
LFS has 75's on sale for 85 bucks! I really think this is "false economy" and bordering on Russian roulette. If you were just using this tank in the garage as a minnow live well, I'd say "Go for it, who cares if the thing explodes!" But inside a home, this is a gamble I wouldn't take... But that's just me. I mean for less than the cost of a good canister filter you can replace the entire tank: I'd just do that rather than risking a repair job.
Be sure to post pics if you attempt the repair!
