Yes, you are right my pool is aluminium. and not steel...my bad Another way I can get around the "PT" vs aluminium corrosion, is replace the "PT" with kiln dried wood painted. I planned on painting the wood white anyway to make it look better. But, on the "PT" vs aluminium ....The "PT" wood running parallel to the ground on the bottom that you see in the picture have been there against the pool walls since I've owned the house (14years). And there is no signs of corrosion. As for the support of the 2x4s...screwed in outdoor deck screws at an angle at the botton and plus added a metal brace (see bottom of support)...seems pretty sturdy. The flexing isn't enough to rip those screws out.