This article is from the Aquaria Newsgroup Topics and Conversion Tables FAQ, by Todd Zebert and Erik Olson with numerous contributions by others.

In metric, this calculation is quite easy because 1 cubic centimeter

of water has a mass of 1 gram, or 1 liter of water has a mass of 1 kg.

Thus, the water in a 200L tank will have a mass of 200 kg (don't

forget to add the weight of rocks into your estimate!). If you need to

work from tank dimensions, multiply the length times width, times

height in centimeters to obtain the mass in grams.

For those of us having to work in inches and pounds,

1 gallon of water at 4°C = 8.57 lbs approximate weight

One foot of fresh water depth = .445 psi.

231 cu inches (in ^ 3) = 1 gallon

1 cu foot (ft ^ 3) = 7.48 gallons = 1728 in^3

Example:

44x16x16 tank = 11264 in^3 = 48.76 gallons.

Tank will weigh 418 lbs (roughly) (+ rocks which have an SG much

higher than 1, so you can *roughly* say " + rocks ")

The pressure at the bottom of the tank will be 0.59 psi, or 85 psf,

roughly 13% more than the standard loading for code construction, so

catch an extra joist or three with the stand!!

Along the bottom strip of the tank, you will have a total (uniformly

spread side to side) force of ( 15.5/12*.445*44 = 25 lbs) pushing

outwards against your joints.

The total force on the long side will be ( 8/12*.445*44*16 = 208

pounds).

Note: In general, this is NOT half of the water weight. This is a

coincidence due to the same bottom and side shape.

Other useful points...

Weight = psi at bottom * bottom area

( (44x16=704 in^2) * .445*16/12 = 418 lbs)

Note: If this doesn't give you the same answer as the volume

calculation SOMETHING IS WRONG!

Standard (new) wood joist floor loading is 75 psf. This corresponds to

one 14" high tank of any other dimensions. Before you build that 30"

high tank, think about where it goes! For old houses and houses not to

code, this may be worse (or better, who knows?).

Common tank sizes (courtesy of All-Glass Aquariums)

These match the table on the back of Catalog AA693, but are sorted by

the tank's "footprint".

Tank Size Exact Outside Dimensions Weight Weight Tempered (inches) (L x W x H) Empty Full Bottom (Including frame) (lbs) (lbs) 10 Leader 20 1/4 x 10 1/2 x 12 9/16 11 111 15 High 20 1/4 x 10 1/2 x 18 3/4 22 170 20 X-High 20 1/4 x 10 1/2 x 23 3/4 32 232 10 Long 24 1/4 x 8 1/2 x 12 5/8 16 116 15 Show 24 1/4 x 8 1/2 x 16 5/8 22 170 15 Gallon 24 1/4 x 12 1/2 x 12 3/4 21 170 20 High 24 1/4 x 12 1/2 x 16 3/4 25 225 25 Gallon 24 1/4 x 12 1/2 x 20 3/4 32 282 30 X-High 24 1/4 x 12 1/2 x 24 3/4 41 340 20 Long 30 1/4 x 12 1/2 x 12 3/4 25 225 29 Gallon 30 1/4 x 12 1/2 x 18 3/4 40 330 37 Gallon 30 1/4 x 12 1/2 x 22 3/4 45 415 X 26 Flatback 36 1/4 x 12 1/2 x 16 5/8 42 300 X 23 Long 36 1/4 x 12 5/8 x 13 32 253 30 Gallon 36 1/4 x 12 5/8 x 16 3/4 43 343 38 Gallon 36 1/4 x 12 5/8 x 19 3/4 47 427 45 Gallon 36 1/4 x 12 5/8 x 23 3/4 66 515 X 30 Breeder 36 3/16 x 18 1/4 x 12 15/16 48 348 40 Breeder 36 3/16 x 18 1/4 x 16 15/16 58 458 50 Gallon 36 7/8 x 19 x 19 5/8 100 600 65 Gallon 36 7/8 x 19 x 24 5/8 126 775 33 Long 48 1/4 x 12 3/4 x 12 7/8 52 382 X 40 Long 48 1/4 x 12 3/4 x 16 7/8 55 455 X 45 Long 48 1/4 x 12 3/4 x 19 60 510 X 55 Gallon 48 1/4 x 12 3/4 x 21 78 625 X 60 Gallon 48 3/8 x 12 7/8 x 23 7/8 111 710 X 80 X-High 48 7/8 x 14 x 30 3/4 200 990 75 Gallon 48 1/2 x 18 1/2 x 21 3/8 140 850 90 Gallon 48 1/2 x 18 1/2 x 25 3/8 160 1050 110 X-High 48 7/8 x 19 x 30 3/4 228 1320 120 Gallon 48 1/2 x 24 1/4 x 25 1/2 215 1400 100 Gallon 72 1/2 x 18 1/2 x 19 3/8 182 1150 125 Gallon 72 1/2 x 18 1/2 x 23 3/8 206 1400 150 Gallon 72 1/2 x 18 1/2 x 28 1/2 338 1800 180 Gallon 72 1/2 x 24 1/2 x 25 5/8 338 2100 2 1/2 Mini 12 3/16 x 6 1/8 x 8 1/8 2.6 27 5 1/2 Gallon 16 3/16 x 8 3/8 x 10 1/2 7 62 4 Designer 8 1/4 x 8 1/4 x 18 7/8 9 49 6 Designer 8 1/4 x 8 1/4 x 24 7/8 10.5 70 10 Designer 13 5/8 x 13 5/8 x 19 18.5 115 15 Designer 13 5/8 x 13 5/8 x 25 25.5 175 10 Hexagon 14 1/2 x 12 9/16 x 18 3/4 12 110 20 Hexagon 18 3/4 x 16 1/4 x 20 5/8 23 220 X 35 Hexagon 23 1/4 x 20 3/16 x 24 3/4 43 390 X 60 Hexagon 27 1/4 x 24 1/8 x 29 1/2 110 750 X

Continue to: