Engineer
**** strait, RTR. I dunno about you Yankees, but 800G of water if I have my facts straight, is over 6-1/2 Short tons in your units. Just over 3T in our Metric units; if this is not resting on a concrete slab, you need some serious consultation.
I know a dude that made tanks of such dimensions (recently), we be talking 3/4" Lexan or greater to house sharks and such for rich people, and the tank design itself was not terribly difficult, though the structural modifications to support several tons of water (typically involving 6" Wide Flange structural beams welded to form a sub-frame) were not uncommon, though poured concrete was viable as well. Not a practical retrofit; He (acquaintance) only did jobs for new home builders as opposed to retrofits.
And the equipment never mind the water adds weight, but alas, that is an awful lot of water. Consult an authority.
DHM