I know this discussion is long past, but polyester resin by itself (either sprayed or rolled) is NOT a good choice for waterproofing/coating wood. By nature, it is very brittle and will crack far easier and quicker than epoxy resin. It is not a glue like epoxy is. Epoxy will give you a better chemical and mechanical bond, where-as polyester is really just a (weak) mechanical bond. Add some chopped strand mat or a biaxial with poly resin and you'll be good. Use poly resin by itself and I will put money on the table that it is cracked within 12 months.
Now, with that said, I like the look of your tank. It looks like something I would put in my basement (if I had one)!
Now, with that said, I like the look of your tank. It looks like something I would put in my basement (if I had one)!