The bigger the tank, the less changes in water chemistry for sure. However, water changes are time consuming with a tank that size.
B4 buying it, consider the filtration and heating needed. Also, the space for the plumbing and the electrical supply for all the devices you are going to attach.
That tank, alone, must weight about 200kg, plus about 2700kg for the wter, plus stand, it will easily pass the 3 tons. Have someone who knows check your floor.
Money would be something to make me think, since every water change (assuming a weekly 20%) will require a lot of water -150gl-, chlorine removers and any other chemichals you might use. Lighting will cost also a bit.
Also, you must be very careful with diseases: treating the whole tank with medicine would be very costly, and going for isolation, catching a specific fish in such a big tank will be hard.
If you can pass over these conditions, I will be the first to be jealous for such an amazing tank. If I had the space needed for something like that, I'd also like to have one.