TinyTanker - Thank you. I will definately take that in to consideration. I do have the room plumbed for a utility sink, so I will tap off the supply and drain for the ro/di unit. I am also looking in to an exaust fan with a humidistat to control heat and humidity.
I will probably put 3/4" marine plywood on top of the stand with the 3/4" foam above that.
erics3000 - The 4x4's were only available in pressure treated lumber. Everything else I bought was regular wood. Do you think I should replace the 4x4's with 2x4's doubled up or do you think just the legs would be ok pressure treated?
Thank you,