Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
If the wood is particle board REMOVE IT!!!
All the particle board warped rather quickly.
I put 1/2" outdoor rated, painted plywood in there, and they are MUCH stronger. Make sure the plywood is a snug fit. Then it will force the legs slightly apart, and not allow the horizontals to bow. I needed to sort of wedge the plywood in, and it would only fit if the shelves' legs were perfectly square.
I am keeping larger tanks on the shelves. More weight, but the weight is mostly closer to the edges than yours. Still not right over the metal supports, though.
I am using the 3' long shelves.