I am planning to install oak pre-engineered click-lock hardwood in my hi-rise condo. I will put a foam or 2-1 kind of underlayment.

My question is how much weight this kind of product and installation type can bear?
I have a big fish tank with about 400 pounds if it's full. The tank stander surface is about 3 square-foot touching the floor. I am worried my floor will be cracked by this much weight on this small surface. Am I over-worried?

thank you for your input.

My foot measures about 10" x 3". That means my foot is about 0.208 sq ft. I weigh 210 (I'm 6'3", but could still stand to lose a few). That means that if I stand on one foot, I am putting 210 / 0.208 pounds per square foot on the floor, which works out to about 1010 lbs/sq ft or 7 psi.

Your fish tank puts down 400/3 or 133 lbs/sq ft (0.92 psi) on the floor. As long as the structure of your house can support 400 lbs (it can), then you should be fine.

On the other hand, if your fish tank stand has, say, four little 1 square inch feet on it, then the equation changes. Now you are looking at 14,400 lbs/sq ft (100 psi) of force exerted. That may give you dents. I'm more a math guy than a flooring guy, maybe someone else can follow-up with what a floor can take without denting. If you use a foam underlayment, the deflection of the foam under those spots would allow movement as well as the compression, which could cause some cracking. To play it safe, I would cut a piece of 3/4" plywood to the size of the stand and place the stand on that. That will distribute the weight evenly over the 3 sq ft and leave you in good shape.

Good luck with your project!

-Chris