By the way, you need to figure at least 12#/gal
. You need to take into account the glass, stand, rock, sand, and even the fish. The water by itself is about 8.5#/gal
. A 90 gal
aquarium averages about 1050#, which is 11.6#/gal
On this note, placing an aquarium against a load bearing wall (typically your exterior wall) is a better choice unless you're on a concrete slab since as you move the weight farther from the load bearing members you increase the shear value on the joists. Most well built houses do not have to worry about anything under 50 gallons, but you could be doing damage to floor joists if you spread load 1000# on a 2x10 or 2x12. This would vary depending on the number of joists you span the load across, but spaning it horizontal to a single joist would cause excessive deflection. There are calculations to all of this that I will not get into, just better to typically play it safe.