rotccapt wrote: my plan for the brace is either a 3 inch wide piece of 1/2 inch acrylic or a 3/8 diameter aluminum rod
Yeah, that would work. Or fiberglassed wood could make a good brace as well. Even a silconed peice of glass will also do the trick.
Even if it does not show any deflection innitially, it will bend over time with out a brace. If it can bend 1/4" thick angle iron (1" sides on the insides) holding 3/4" fiberglassed plywood at only 24" deep, wood is definately going to bend in a 29" deep tank with out being braced horizontally