Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Any of those clear finishes are a good idea, but also make sure that the water cannot creep between parts of the stand and enter the wood through a spot you cannot paint or stain. You might need to caulk those types of joints first to stop the water flowing in that direction.
Mask where you want to caulk and use a clear silicone just like we use for the tanks. 'Window and Door' is fine, 'Kitchen and Bath' is good, too, for stands. K & B is not for inside the tanks. Dap and GE are the 2 product lines I see the most about.