Im posting late in the game and may be repeating previous comments but I have a lot to say. Most of it is based on simple logic.
First off, I dont know what your income is and your retirement funds and will not ask as it is rude, but the cost of set-up and maintence would be astronomical. Almost too much for one to bear alone. You could apply for a government, state, university or foundation grant. Also you could work along side with a local or state aquarium. Check out the AZA website for information and help, as well as listings of local foundations and clubs. There is a marine biology school in Galvisten which could be of help, they may be able to offer voleenter help from students which would give students an excllent oppritunity to study marine life in a large, enclosed and safe enviorement. Im sure if you prove to them that you are genouenly serious about this, they will help. I believe the school also is active with a naval academy. You will also need someone to take over once you are unable to continue maintaining the habitat (like old age, disablity or death; its an ugly thought but it needs to be considered in an undertaking such as this).
Second, filtration and maintence on water and tank repair would be a pain. All of the pool systems would need to be thorougly flushed and clean to rid them of contamintes such as chlorine and other stuff. You would need a massive RO unit as tap water heavy metals would be insane. There may be a way to get accual sea water and filter that extensively. Sea water is also acidic like. A pH of 7.8 to 8.2 has enough base content to eventually wear away at cement. (Base pH is just as bad as acid pH due to its alkilie reactive properties. Example: NaOH(l), liquid sodium-hydroxide, reacts with fat in your skin cells to create soap, wearing away at your epiderumus.) It could do the same with elements contained inside of the cement of your pool. Remember, cement is a mixture, not a compound. You would have to coat the pool in a protective substanace.
Third, the pool would have to be enclosed and seeled inside of a building or structure. Heating the structure would help with keeping the pool temperature stable. But the main purpose would be to protect form rain, which contains acid and contaminents, as well as snow, leaves, grass, trash, insects and animals ( or possibly other people!!). The structure it self could be rigged with the lighting needed for an aquarium as the default lighting system hung form the roof of the structure. You could not use the sun as a source of light since it promotes the growth of hair and slime alge, which are very unpleasent. The suns intensity varies throughout the world due to the pitch and rotation of the planet and often its effects are divesified. You could not use the sun as a good light source. Also, the structure could not be built of brick or glass, external temperature drastically effects internal temperature with these materials without insulation.
Fourth, buying everything in bulk would help to bring the cost down. See if you cant get a hold of the message boards member Requiem. He has a 2,700gallon indoor tank that he did completely on his own and claims he did everything for under $4,000. That would be alot of help. He also says that he has knowledge of the business and is interested in buying in bulk with other people. Importing in seawater would bring the cost down dramatically since you would not need as much salt, RO water and calcium additives. You would need a second isolated large tank to filter the sea water since it will be cloudy and could have some contaments. It could be illegal but i dont see why, there is so much of it that it covers 70percent of the globe.
Some may find this information useless, stupid or repeatitive but the reading in this thread is extensive. I read 3/4ths of the first page and gave up. I am mearly trying to offer some help which could be nessisary. If you find this helpful, please respond so that I know I was successful and did not waste my time writing and editing this. In the future I also would like to wish success to you in your massive undertaking. This is nothing to discourage if you are truely devoted to doing this.
:happyfish
