If you have a basement and have access to the area under your tank, you might want to go to your local hardware store and look at the adjustable jack posts. They come in different strengths, lengths, and prices. It was not for an aquarium or safe but they worked for me.
Not quite what I would do, if you have basement or big enough crawlspace, go get 2 8-10' 2x12's, a tube of liquid nails, and join them together, use some good size nails, (Probably 8 penny nails) On top of the liquid nails, nail the boards together, and orient your nails in different angles. Some angle to the right as you nail in, and some angle to the left. The idea is to not have the nails straight in, and have the angles working against each other to not be able to walk out.
To be a little more anal, on top of the nails, get some 4" screws, and screw the boards together lines of 3, every 2 feet down the length. And off set teh lines of three from teh other side (This is definitely overkill, but hey, whats wrong with a lil over kill?) And voila, you have you strong azz beam. (This is the old school way to support long spans for open concept homes, but they may use 3-4 boards depending on whats above it, or new school will use engineered beams like duralams or something of that nature)
If you have a basement, rent the jacking posts the above poster mentioned, and go get some lolly columns (Steel pipe filled with concrete) These will come with steel plates to attach them to the beam/floor. On the load bearing wall that you plan to put the tank, figure out how far out the front of your stand will be. This is where you want you beam. Place beam in place with the jacking post. (Beam will run the length of the tank, but you want each end of the beam to extend to the joist beyond where the end of your tank stand is) Before you start jacking, take a measurement from the basement floor, to the bottom of the joists. Use the jacks to evenly jack the beam up, NO MORE than a 1/4 inch. Let the jacks hold the weight, while you measure, and prep for the lolly columns. (This can be cut with a large pipe cutter) (That 1/4 inch is JUST meant to give you room to put the lollies in place) Once the lollies are in place, lower the jacking posts, and make sure your back where you started from.
This is assuming that the wall is supported by a wall in the basement. If you question that said wall, then you might want to do this twice with a second beam at the wall to support the tank on both sides.
If your have a crawl space, then you could just use some 4x4's. But if you have a dirt floor, you should pour a concrete pad for these.
No matter what, 2x10 or 2x12 joists will support that weight over a span of 3-4 feet (guessing the size of your stand, and the distance from the front to the wall) , all day, any day. If your place is built with the engineered wood i beams, pay close attention to the spread. I know those suckers will support a lot of weight when placed on 16" center, but contractors sometimes spread them to 20-24" on center. While they are still ok at that spread, it lowers it's load rating. BUT, that beam I just told you about, will reinforce that because those beams wont be spanning 30'-40'.
Just throwing out what "I" would do. Use this suggestion at your own risk.
(Not much of a risk, but that beam would get heavy for one person. LOL)
10 gallon fresh setup with 1 giant danio, 3 placos, and 1 guppie.
30 gal bare bottom QT
55 gallon salt setup with a bunch of crabs and snails. false perc clown, diamond goby, lawnmower blenny, a green mandarin, and 1 cleaner shrimp. And a few corals
180 gallon acrylic not setup yet. (Need a few more things before it gets filled with water.)
Tanks not setup, 10, 30, 55 with stand. Either 30 or the 55 will be the sump for the 180