The pool in the pics are of my quarantine system that is about 2500 gallons. The main pool is in another part of the garage and is the grand daddy at 18000 gallons. I hope to have some pics of the main system up soon ( had a small accident w/ camera- seems they hate saltwater). The QT is a 10 foot diameter, three foot deep swimming pool that I slightly modified to suit my needs. The main pool is a combination of wood and cinder block construction using two 40 mil pond liners. I began by building the basic structure with common cinder block. The demensions are 25 feet long by 18 feet wide by 4.5 feet deep. I used marine grade plywood as a support for the two liners that went in last. I had debated about using two part epoxy but was able to get an excellent deal on the liners. Having two is a safety feature in case one should tear.
The outside of the pool was finished with some nice faux limestone rocks that make the pool appear as if its a large "tide pool", this is a great effect to see. The corners of the pool are in about a 30 degree arc so there are no sharp corners for the shark to get caught in (most free swimming sharks such as the bonnet can not back up).
The filtering system for the display is in another room that was a later addition to the house. This system includes a very large wet/dry, sand filters, three 2.5 hp Jacuzzi pumps, two large protein skimmers, and various probes.