Very Large Display Tank, Help Appreciated

Well I guess we will see what happens as I might be using 2 of the exact same high quality skimmers. Probably something like dual ETSS Quad 3000 Profesionals. Each one is rated for up to 5000 gallons when using a 3/4hp high pressure pump. I figure a max tank load of 10,000gallons should be suffecient for my 5800gallon display, and I have found that ETSS rates their skimers very conservatively. I might end up using 1 large skimmer made of mabey translucent fiberglass but Im unsure at this point, it depends what some of my connections offer me.
About the seawater question... I have thought about trucking in seawater but it is not much cheaper and there is a lack of clean water on the coast of B.C. Buying salt by the pallet makes it a little more affordable and I can also get it by the 2000lb bag for a little cheaper yet.

Anyone have any big tank ideas of their own, things they would do to a large tank???