i have a small bow on the bottom front piece because it had a crown that i apparently thought i'd get out by making it flush with the bottom plywood, well i was wrong...crowns i assume are pretty tough...so i'll be taking care of that, maybe by using a support shim or something so it cant move under the weight of the water...it doesnt move with my standing and pushing force on it so i dont think it'll be too big of an issue, but i'm not 600 lbs of water,rock and sand.