FishMaths

20 gallon long tank: size, liters and setup numbers

The 20 gallon long trades height for length. That extra floor space makes it a favorite for schooling fish, bottom dwellers like corydoras, shrimp, and breeding or quarantine setups.

Typical dimensions30 × 12 × 12 in
76.2 × 30.5 × 30.5 cm
Volume20 US gallons
75.7 liters
Realistic water after substrate and decorAbout 17 gal
About 64.4 L
Water weightAbout 167 lb
About 76 kg
Gravel for a 1 inch bedAbout 21 lb
About 9 kg
Gravel for a 2 inch bedAbout 42 lb
About 19 kg
Heater (room 8°F / 4.4°C cooler)50 W
Heater (room 15°F / 8.3°C cooler)100 W
Filter flow (4 to 6 times per hour)80 to 120 GPH
303 to 454 L/h

Dimensions vary a little between brands. For exact numbers, measure your tank and use the calculators below.

Plan the rest of your 20 gallon long tank

Common questions

How many liters is a 20 gallon long tank?
A 20 gallon long tank holds about 75.7 liters when filled to the brim. With substrate and decorations, the real water volume is usually closer to 64 liters.
How much does a 20 gallon long tank weigh when full?
The water alone weighs about 167 pounds (76 kg). Glass, substrate and rock add more on top, so choose a stand rated for the full weight.
What size heater does a 20 gallon long tank need?
If your room stays around 8°F below your target water temperature, a 50 W heater is a good fit. For colder rooms, around 15°F below target, go with 100 W.

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