It Ain't Heavy; It's My Aquarium
by Robert W. Bly, founder, AquariumDetective.com
One overlooked aspect of the aquarium hobby is the weight of the tank.
The tanks themselves are not that heavy, but the water in the tank is - about 8 pounds per gallon for freshwater and slightly over that for saltwater.
That means your 120-gallon tank holds almost a thousand pounds of water!
The weight of water makes carrying a filled fish tank by hand difficult. I have carried a 10-gallon tank filled with water and goldfish from someone's car to their apartment, but it's not advisable.
The 80-pound weight is manageable, but it's not good for the tank. Carrying a filled tank can cause the glass to come apart at the seams, resulting in a leak and rendering the tank unusable.
Another problem with the weight of filled fish tanks is the stress on the stand. Since fish tanks are heavy when full, I advise you to buy a stand designed for that size tank.
Not only do the prefabricated stands look attractive and have useful features (such as storage cabinets for supplies, pumps, and filters), but they are built to handle the weight of the full tank.
You can build your own tank stand out of 2 by 4's, but if you do, add double supports at each corner plus some cross support beams.
The stand should be painted or varnished. This improves appearance and protects the wood from spills when you are changing tank water or adding specimens from bags.
I recently made a big mistake: I set up a 40-gallon tank in my son's room on a wooden desk he had. I used the desk so I wouldn't have to throw it out and buy an expensive fish tank stand.
When I filled the tank, the desk was clearly bowing under the 320 pounds of water weight. My solution was to run out and buy six 4-by-4 pieces of lumber cut to the height of the desk.
I placed the six beams upright under the desk, and used shims to keep them firmly in place. But from now on, I buy a stand.
The weight of a large tank may pose a problem in a house not constructed to support that weight, particularly on a second-floor room addition.
If you are adding a room and plan to have a large tank, tell the contractor the approximate weight and require him to build the floor to support the biggest tank you would consider getting. For a 200-gallon tank, that's 1,600 pounds for the water. I'd specify 2,000 pounds to be safe.