The stand looks good I think as long as you have supports under the top of the stand, But Im not a carpenter just my 2 cents. Also what size sump is that, and Im not really sure but I thins if you sectioned off half of it and did a wet dry though a very large spray bar that had bunch of drip holes and large pvc it would spread out the spray and slow it down enough over the bio to get it growing good, the bio grow the most efficient when there is a lot of oxygen, there for wet drys are way more efficient than lets way a canister filled with bio. Also if you have a high gph flowing fast enough through the sump it make it very hard to grow Beneficial bacteria at all. Im wanting to say that it grow the best around 1000gph and under. Sry if you lost me I had trouble trying to put what I was thinking into words.