Gregcoyote
Aquarium Advice Addict
So yeah it would be 5 grand for salt for a BIG tank that is 15 thousands gallons. So right there you are already looking at 7 grand, than add the filters and heaters you are in the 10 grand range for even a pool tank. PLUS if you want to cut unto the metal to provide a few port holes to look into too, that will add to the cost and risk of tank failure.
It would also need to sit somewhere where it would stay under 80F year round. More likely expensive chillers needed. Plus 15000 gallons of saltwater in a above ground pool sounds like a disaster waiting to happen. Cleaning it? Stocking it? I think I'll let somebody else try this.