How much substrate do I need for a 40 gallon breeder tank?

For a 91 x 46 cm footprint at a 3 inch average depth you need about 32 litres: roughly 32 kg of aqua soil or 48 kg of sand. At 2 inches it is 21 litres.

What size heater for a 40 gallon breeder planted tank?

A 100 W heater. Once substrate and rock are in, a 40 gallon breeder holds about 129 litres (34.1 gallons) of water, which works out to 2.9 W per gallon.

How much filter flow does a 40 gallon breeder planted tank need?

Aim for 520-770 litres per hour, which turns the water over 4 to 6 times an hour. Planted tanks like steady, gentle flow rather than a jet.

How much substrate do I need for a 40 breeder?

About 3 inches on average (2 at the front, 4 at the back) is roughly 30 litres of aqua soil. See the substrate figures on this page for the exact number at other depths.

40 gallon breeder planted tank setup

The aquascaper favourite: 18 inches front to back gives real depth to a layout, and 16 inches of height keeps light at the substrate.

Dimensions: 91x46x41 cm; 36 x 18 x 16 in outer
Water volume: 129 L; 170 L (44.9 gal) gross, less substrate and rock
Substrate, 3 in average: 32 L; 32 kg aqua soil or 48 kg sand
Heater: 100 W; 2.9 W per gallon
Filter flow: 520-770; litres per hour, 4-6x turnover
Light timer: 7-8 hours; with CO2 running

Lighting

A 91 cm tank needs a bar that covers the full length so the ends do not go dark. The 46 cm front-to-back depth is wide for one bar; two bars or a centre mount gives even coverage.

Fits this tank

Aurora Smart 78 — RGB App-Controlled LED

78 cm bar, fits 70 to 95 cm tanks; your tank is 91 cm long.

$80

Filtration

Target 520-770 L/h, which is canister territory. Our filters top out around 100 L, so pair a canister rated for at least 130 L with our media: ceramic rings for bacteria, foam pads for mechanical.

CO2

Recommended. At 129 litres a pressurised system is the easiest way to hold steady CO2 for carpets and stems.

CO2 option

CO2 Starter Kit - Regulator, Diffuser & Checker

Regulator with solenoid, atomiser and drop checker; you add a refillable cylinder.

$110

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

21 L

21 kg soil, 32 kg sand

3 in average

32 L

32 kg soil, 48 kg sand

4 in average

42 L

42 kg soil, 64 kg sand

Custom tank? Use the substrate calculator

What to plant

Suits: Full nature aquarium or iwagumi with a deep foreground and layered hardscape.

Dwarf hairgrass or Eleocharis carpet
Bucephalandra and Anubias on rockwork
Rotala and Ludwigia groups for colour at the back
Cryptocoryne along the hardscape edges

Fish and shrimp

A large school (20 or more) of one small species reads best in an aquascape, plus otocinclus and amano shrimp for algae.

Mistakes that cost people this tank

1Single light on a deep tank. 18 inches front to back leaves the back row dim with one bar; run two or mount one at the centre line.
2Not enough rock. A convincing layout in 40 gallons needs more hardscape than people expect; buy for the layout, then remove.
3CO2 under-dosed. At 150 litres, a small DIY bottle runs out quickly; a pressurised regulator is easier to keep stable.

Quick answers

How much substrate do I need for a 40 gallon breeder tank?: For a 91 x 46 cm footprint at a 3 inch average depth you need about 32 litres: roughly 32 kg of aqua soil or 48 kg of sand. At 2 inches it is 21 litres.
What size heater for a 40 gallon breeder planted tank?: A 100 W heater. Once substrate and rock are in, a 40 gallon breeder holds about 129 litres (34.1 gallons) of water, which works out to 2.9 W per gallon.
How much filter flow does a 40 gallon breeder planted tank need?: Aim for 520-770 litres per hour, which turns the water over 4 to 6 times an hour. Planted tanks like steady, gentle flow rather than a jet.
How much substrate do I need for a 40 breeder?: About 3 inches on average (2 at the front, 4 at the back) is roughly 30 litres of aqua soil. See the substrate figures on this page for the exact number at other depths.