# Re: [Killietalk] Tank weight

```      A reef tank is a beautiful amenity that the owner enjoys showing
visitors. Its location and size should be decided early, with the living
room or den usually the first choice. The underlying floor support - 2 x 4"
wood frame studs, concrete - limits maximum tank size. A concrete floor in a
den is usually risk-free, but watch for cracks in a settling house than can
shift the floor into uneven planes. Although a wooden stud floor in a corner
should support the weight of a large reef tank, even a slight sag poses the
risk of stress on the glass bottom resulting in sudden panel separation or a
cracked glass. The strongest location on a wooden floor is a corner.

The typical reef tank is 70-135 gallons. It is set up with 1-2 pounds
of rock (see Chapter 4) per gallon tank size, and often two to four inches
of sand or gravel. The remaining 75 percent of tank capacity will be filled
with water. Let's calculate the weight of any tank fully set up.

The weight of the average tank and stand is a little more than 1.5
pounds per gallon, more for larger tanks. A 55 gallon tank and stand will
250 pounds. About 75 percent of the tank will be filled with water weighing
8.25 pounds per gallon. About 25 percent of the tank will be occupied by
rock and sand or gravel. Estimate the rock and sand/gravel at 17 pounds per
gallon or 17 pounds times 25 percent of the gallon capacity of the tank.

Let's estimate the weight of a 135 gallon set-up. We're already
estimated tank and stand at 250 pounds. Next, measure the base of the tank.
A 135-gallon tank will be 18 inches back to front (wide), and 72 inches side
to side (long), equal to 6 x 1.5 feet or 9 square feet. Using the square
foot method to calculate the aragonite gravel needed, estimate 6.5 pounds
per inch of gravel depth per square foot of tank bottom. For three inches of
aragonite gravel you will need 6.5 x 3 x 9 or 175.5 pounds of gravel. It
comes in 44-pound sacks, so four sacks will be just right (4 x 44 = 176).
The square inch method to calculate the pounds of aragonite sand needed to
fill a tank to a particular depth is to multiply L x W x D (where D is depth
of sand desired) in inches, divide the product by 1728, and then multiply by
70.

A 135-gallon tank is 24 inches high. After adding 3 inches of gravel,
another 3 inches will be displaced by 1-2 pounds per gallon of live rock. At
a minimum, the rock will weigh 135 pounds. If the tank is filled 75% with
water, the water alone will weigh 835 pounds. And so the total weight of a
135 gallon reef tank in pounds = 250 (tank and stand) + 176 (gravel) + 135
(rock) + 835 (water) = 1,396 pounds or almost three quarters of a ton, with
the weight distributed to four or six legs of the stand.

The weight of a reef tank precludes using household furniture as
wooden stands should be constructed of 4x4 or larger pressure-treated lumber
and have numerous deeply screwed cross braces to protect against warping.

You cannot overbuild a stand.

Every large tank should be sandwiched on a half inch styrofoam
platform to absorb slight unevenness where the tank bottom meets the top of
the stand. Every stand should be shimmed to eliminate the slightest
unevenness.

Finally, leave enough distance between the tank and any walls (4-6
inches) for the dissipation of heat. Keeping a reef tank cool is a difficult
problem, and open space can be a great aid to its solution.

----- Original Message -----
From: "wm crash" <wm_crash at hotmail_com>
To: <killietalk at aka_org>
Sent: Wednesday, December 20, 2006 3:57 PM
Subject: [Killietalk] Tank weight

> Hi,
>
> How can I figure out how heavy of a tank I can safely place in my house ?
> The floor I am looking at has carpet without the additional reinforcement
> that one would need for tile for example.
>
> cheers,
> wm_crash, the friendly hooligan
> AKA #08840, SAA #162, SVAS #120, HOOLIGAN #1
> Wilmington, DE
>
> _________________________________________________________________