Gross vs actual volume
36 × 18 × 16 in multiplies out to 44.9 US gallons, but that box includes the glass and runs to the very top of the frame. Taking off 6 mm of glass on each side and the base, and filling to 1 inch below the rim, leaves about 39.8 gallons of water. Gravel, rock and wood take that down further; the volume calculator estimates it for your aquascape.
How much a filled 40 gallon breeder weighs
| Water | ≈ 305 lb |
| Glass | ≈ 51 lb |
| Gravel (2 in) | ≈ 72 lb |
| Total | ≈ 428 lb |
|---|
Water weighs 8.34 lb per US gallon, so it is most of the load. Put the tank on a stand rated for it, level, and supported under the whole frame. More on this in how much a fish tank weighs.
Heater and filter
Holding 78 °F in a 68 °F room with a lid takes about 150 W of heater, using the same heat-loss model as the heater calculator (compare sizes on the heater size comparison). For filtration, a common target is turning the water over 4–6 times an hour: 159–239 gallons per hour of rated flow.
Frequently asked questions
What are the dimensions of a 40 gallon breeder tank?
A standard 40 gallon breeder aquarium is 36 × 18 × 16 in (length × width × height), or about 91 × 46 × 41 cm. These are outside dimensions; brands differ by a fraction of an inch.
How many gallons does a 40 gallon breeder tank actually hold?
Its outside dimensions work out to 44.9 US gallons (170 liters). Inside the glass, with the water about an inch below the rim, it holds roughly 40 gallons (151 liters), and less once gravel and rock go in.
How much does a 40 gallon breeder aquarium weigh when full?
Roughly 428 lb (194 kg): about 305 lb of water, 51 lb of glass and 72 lb for a 2 inch gravel bed. Rock, decor and the stand add to that.
What size heater does a 40 gallon breeder need?
About 150 W to hold 78 °F in a 68 °F room with a lid. A colder room or an open top needs more; the heater calculator works it out for your conditions.