treated plywood or marine grade plywood would be my suggestion. even if the mdf is sealed with time it won't uphold. What pump system with you be running this bad boy on?
I've not chosen any hardware for this yet but i like to do things that arnt the norm i will be using ply now but now its the thickness of the ply
when using the mdf i was using 18mm with over the top bracing and strengthening any idea on the ply thickness anyone