My diatribe, hope it isn't too muddled.
Tank prep
I started with a 55 gallon tank that I had sitting around for the last 15 years. I bought a couple of tubes of silicone sealant and resealed all the inside corners and most importantly under the top frame. The top frame had come loose when I was using it as a freshwater and water would wick up over the glass and dribble down the sides. So I removed the whole top frame and squeezed a whole tube inside the notch where the glass goes. Then mushed the frame back down on the glass and applied 2 cotes of sealant around the inside.
Stand
I had an iron stand from fish keeping years of old which I repainted.
Placement
I set the stand up in the basement against a wall of the utility room. This wall had a heater vent about a foot from the floor, which placed it behind the lower 40 gallon tank. I relocated this heater vent to about 5