I just read that article about the 1700 gallon wood shark tank. It seems like doing the fiberglass and the sanding was very difficult.
I noticed you used "pond shield two part epoxy" to waterproof the concrete block. I've never used that product. How does it compare with the sealing process that Joe S. did on his wooden tank? I assume it is easier.
Joe S. did say he would have preferred to do a concrete tank, but had to consider the resale of his house. Do you think that if resale is not a factor, concrete is the best way to go for a massive tank?