Help with fisk tank stand size!!!

I honestly don't trust any store bought stands in an area I don't want to get wet. I build my own stands, but you could always reinforce that stand with a few 2x4's and some deck screws.

Accommodating the weight of water, the tank itself, and substrate, that 90g tank should turn out to be roughly 900 lbs when full. (calculated for 90g of water @ 8 lbs/gal, 75 lbs substrate, and 100lbs for tank, comes out to 895) This is under the assumed pretense that anything you put in the tank will not displace water volume (which of course it will) so the actual weight would likely hover slightly under 900 lbs. Now, this is just coming from someone who is a little over-precautions about this stuff, but if the stand can't hold 1.5x the weight of the tank, I wouldn't use it. The stand is rated for 900 lbs, so if it did fail, you might be able to claim something with the company which made it, but don't count on it. A 4'x2' table would easily hold an empty 75g tank, (the size of the table my pc is on) but I would never put a full 75g tank on this table. My honest opinion would be to return the stand you bought, and build yourself a much stronger stand. Supplies will likely cost you something like $60-$100, and perhaps 8-12 hours of labor on your part. (depending on how you design it, how you want to finish it, etc.)

My Perfecto stand for my 210 literally scared the hell out of me when I first laid eyes on it....it weighs about 60 lbs and is made entirely out of 1x4s. But it has held my tank full of water and rocks and sand which weighs in around 2200 lbs for a year with no problems.
I don't know if this helps you or not
Robbie