I have a double metal stand used for my 40g breeder tanks, it's sitting in my garage because I switched to a 75 gallon set up. I would like to use that stand for 2 20 gallon long tanks, can I put a piece of wood to make a solid surface for the 40 breeder size and put a 20 long on it? One 20 gallon tank has 10-15 lbs of sand, 6 gallons of water, and a fiddler crab. The other 20 gallon tank is for my floaty oranda, it has 5 gallons of water, bare bottom. As always, safety first so if it's questionable in any way I won't do it but if it's perfectly fine I'll go with that. Thanks!