How much substrate do I need for a 20 gallon high tank?

For a 61 x 30 cm footprint at a 3 inch average depth you need about 14 litres: roughly 14 kg of aqua soil or 21 kg of sand. At 2 inches it is 9 litres.

What size heater for a 20 gallon high planted tank?

A 50 W heater. Once substrate and rock are in, a 20 gallon high holds about 57 litres (15.1 gallons) of water, which works out to 3.3 W per gallon.

How much filter flow does a 20 gallon high planted tank need?

Aim for 230-340 litres per hour, which turns the water over 4 to 6 times an hour. Planted tanks like steady, gentle flow rather than a jet.

Can you carpet a 20 gallon high?

It is harder than a 20 long because the substrate sits 16 inches from the light. Use a stronger light and CO2, or choose shade-tolerant ground cover like crypts.

20 gallon high planted tank setup

A taller column of water on a smaller footprint. Great for stem plants and vertical wood, harder for carpets.

Dimensions: 61x30x41 cm; 24 x 12 x 16 in outer
Water volume: 57 L; 76 L (19.9 gal) gross, less substrate and rock
Substrate, 3 in average: 14 L; 14 kg aqua soil or 21 kg sand
Heater: 50 W; 3.3 W per gallon
Filter flow: 230-340; litres per hour, 4-6x turnover
Light timer: 6-7 hours; without CO2

Lighting

A 61 cm tank needs a bar that covers the full length so the ends do not go dark.

Fits this tank

Aurora 48 Planted Tank LED Bar

48 cm bar, fits 48 to 61 cm tanks; your tank is 61 cm long.

$73

Filtration

Target 230-340 L/h for a planted tank this size.

Right-sized filter

Hang-On-Back Waterfall Filter — 3-Stage, 250 L/H

250 L/h hang-on-back, rated for tanks up to about 80 L.

$17

CO2

Optional. Low-light plants grow without it; add CO2 if you want a carpet or red stems.

CO2 option

DIY CO2 Generator Kit — 2 L Stainless

Refill-free citric acid kit; enough for a tank this size without a gas cylinder.

$66

Substrate by depth

Slope it: shallower at the front glass, deeper at the back. The average depth is what sets how much you buy.

2 in average

9 L

9 kg soil, 14 kg sand

3 in average

14 L

14 kg soil, 21 kg sand

4 in average

19 L

19 kg soil, 28 kg sand

Custom tank? Use the substrate calculator

What to plant

Suits: Vertical driftwood scape with tall stems and epiphytes.

Tall stems: Limnophila, Hygrophila, Rotala
Spider wood with java fern and moss climbing it
Cryptocoryne wendtii in the shade under wood
Amazon frogbit to soften the light

Fish and shrimp

Mid-water swimmers suit the height: a pair of honey gouramis with a school of 10 lemon tetras.

Mistakes that cost people this tank

1Expecting a carpet. At 16 inches tall, light at the substrate drops off; pick plants that tolerate shade at the bottom.
2Weak circulation. Tall tanks stratify; point the filter return along the surface so water rolls top to bottom.
3Short light. The tank is 61 cm long; a 48 to 61 cm bar is the right fit.

Quick answers

How much substrate do I need for a 20 gallon high tank?: For a 61 x 30 cm footprint at a 3 inch average depth you need about 14 litres: roughly 14 kg of aqua soil or 21 kg of sand. At 2 inches it is 9 litres.
What size heater for a 20 gallon high planted tank?: A 50 W heater. Once substrate and rock are in, a 20 gallon high holds about 57 litres (15.1 gallons) of water, which works out to 3.3 W per gallon.
How much filter flow does a 20 gallon high planted tank need?: Aim for 230-340 litres per hour, which turns the water over 4 to 6 times an hour. Planted tanks like steady, gentle flow rather than a jet.
Can you carpet a 20 gallon high?: It is harder than a 20 long because the substrate sits 16 inches from the light. Use a stronger light and CO2, or choose shade-tolerant ground cover like crypts.