Aquarium plants without CO2

Not every planted tank needs a CO2 system. These plants grow well without injected CO2, so you can keep a green tank with less equipment. Each profile lists the light and placement a plant prefers.

Height: 0–59.1 in; 0 in (0.1 cm) to 59.1 in (150 cm); half the list stays at 9.8 in (25 cm) or under
Temperature: 68–82°F; 20–28°C, most of the list
Light: 66 low light; 36 medium light · 8 high light
Growth: 55 slow growing; 15 medium growth · 40 fast growing
Difficulty: 104 easy; 6 medium

77 plants and 33 varieties

Start here

The plants that do not need CO2

The java fern lists CO2 as unnecessary and grows in low light tied to wood, 11.8 inches (30 cm) tall, marked beginner. The anubias nana is the same rating at 4.7 inches (12 cm). The cryptocoryne wendtii is the rooted plant, marked beginner for low light, 9.8 inches (25 cm). The vallisneria spiralis spreads by runners to 19.7 inches (50 cm) with no CO2 and no fuss. The hornwort grows fast in any light and never needs planting. The amazon frogbit floats, marked beginner, with roots that trail 2 inches (5 cm) into the water.

The rule

What this list filters on

Every plant here lists CO2 as not needed, which is a stronger claim than beneficial: the plant grows at full health on the carbon a stocked tank makes on its own. That works because the light stays low or medium, since strong light without carbon grows algae instead. Liquid carbon is optional, and two plants on this page dislike it: the vallisneria and the hornwort often melt under a liquid carbon dose. Fish and food supply the rest, and a root tab under the crypts and vals covers what they take from the substrate.

01
None means none
Not merely beneficial: full growth without it
02
Low or medium light
Strong light without carbon grows algae
03
The tank makes the carbon
Fish, food and mulm supply enough
04
Liquid carbon is optional
Vallisneria and hornwort melt under it

Stems

Stems that grow without CO2

The Canadian waterweed is marked beginner for low light, a stem that grows to 23.6 inches (60 cm) and roots wherever it lands. The hygrophila polysperma is the same rating at 17.7 inches (45 cm). The Brazilian pennywort grows fast to 19.7 inches (50 cm) with round leaves on a creeping stem. The creeping Charlie is 15.7 inches (40 cm) of the same habit. The moneywort is a slow, upright stem with round leaves at 11.8 inches (30 cm), marked beginner. The ambulia is a feathery stem marked easy for low light at 15.7 inches (40 cm).

Rhizomes

Rhizomes and mosses

The anubias barteri is the big anubias at 13.8 inches (35 cm), marked beginner, and the anubias petite the small one at 2 inches (5 cm), marked easy. The Windelov java fern has lace-cut leaf tips, the trident java fern forked ones, and both are marked beginner with the plain fern's care. The java moss is marked beginner and grows on anything. The willow moss is the cool-water moss, marked easy at 4.7 inches (12 cm). All of them are tied to wood or rock with the rhizome in the water, never buried.

Rooted

Rooted plants without CO2

The cryptocoryne wendtii red is marked beginner for low light, the red plant for a tank without CO2 at 5.9 inches (15 cm). The cryptocoryne spiralis is the tall crypt at 13.8 inches (35 cm). The giant vallisneria reaches 59.1 inches (150 cm) and lies along the surface in a normal tank; the dwarf vallisneria stays at 15.7 inches (40 cm). The Echinodorus palifolius is a sword marked easy with no CO2 that reaches 39.4 inches (100 cm). The Crinum calamistratum is a bulb with crinkled leaves to 23.6 inches (60 cm), marked easy for low light. All of them want a root tab.

Floating

Floating plants

Floating plants take their carbon from the air, so none of them needs CO2. The dwarf water lettuce is marked beginner, a rosette at 3.9 inches (10 cm) with hanging roots. The salvinia natans is a floating fern marked beginner that doubles every couple of weeks. The red root floater turns red under strong light at the surface. The water spangles is a larger salvinia, marked easy. The duckweed is marked beginner and impossible to remove once it is in. The floating water sprite grows as a loose fern at the surface, marked easy, 15.7 inches (40 cm) across.

By the numbers

Smallest

Tallest

Low light

Fast growers

FAQ

Common questions

Which aquarium plants grow without CO2?

The java fern, anubias, java moss, cryptocoryne wendtii, vallisneria, hornwort and every floating plant list CO2 as not needed. Every plant on this page does.

What is the difference between no CO2 and CO2 beneficial?

A plant marked none grows at full health without it. A plant marked beneficial grows without it but grows faster, fuller or redder with it. The plants on this page are the first kind.

Do I need liquid carbon?

No. It is optional for every plant here, and the vallisneria and hornwort often melt under it.

How much light for a tank without CO2?

Low or medium. Strong light without carbon grows algae, so keep the fixture at the lower end of its range and the photoperiod at six to eight hours.

Do plants without CO2 still need fertilizer?

Yes, in small amounts. A root tab under the crypts, swords and vals, and a liquid fertilizer at half dose for the stems and floaters.

Which no-CO2 plants grow fastest?

The hornwort, Canadian waterweed, hygrophila polysperma, Brazilian pennywort and the floating plants. They are what keeps a tank without CO2 free of algae.

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