Carpet plants without CO₂: what works in a low-tech tank
Oct 4, 2026 · 4 min read
Carpet plants that grow without injected CO₂: dwarf sagittaria, dwarf hairgrass, Cryptocoryne parva, Marsilea and moss on mesh, with light and planting tips.
You can grow an aquarium carpet without injected CO₂, but only with plants rated for it and with more patience. In the catalog, the carpeting plants that need no added CO₂ are dwarf sagittaria, dwarf hairgrass, Cryptocoryne parva, Marsilea hirsuta and the aquarium mosses. Dwarf sagittaria is the fastest of them. Java moss tied to mesh gives a moss carpet straight away. Plants such as dwarf baby tears and Glossostigma are rated as needing CO₂ and are better left for a high-tech tank.
What changes without CO₂
Buce Plant says carpets are the plants furthest from the light, so they need strong lighting, and suggests 8 to 10 hours of light a day. It also warns that low-tech carpets grow slowly: a microsword carpet can take months to fill in without CO₂.
Carpet plants rated for no added CO₂
- Dwarf sagittaria: grass-like rosettes that spread by runners. Rated easy and fast-growing, for medium light, no added CO₂. Buce Plant calls CO₂ optional for it and one of the easiest carpeting plants for low-tech tanks, with CO₂ speeding it up.
- Dwarf hairgrass: fine, grassy tufts 3 to 5 cm tall. Rated easy, for low to high light, no added CO₂. Buce Plant lists it among carpets that work without CO₂ if the light is strong enough.
- Cryptocoryne parva: the smallest crypt here, 5 to 10 cm, for low to medium light. Rated slow, so it fills in over a long time.
- Marsilea hirsuta: a clover-like carpet 3 to 5 cm tall, rated easy and slow, for medium to high light. Buce Plant describes the Marsilea species as slower but less demanding of direct light.
- Aquarium mosses such as flame moss, weeping moss and peacock moss: rated easy, for low to medium light, no CO₂, slow.
Java moss carpet on mesh
A moss carpet is made, not planted. Buce Plant’s moss on mesh is laid straight on the substrate as an instant carpet, rated for low to medium light with CO₂ optional. You can make the same thing by spreading a thin layer of java moss over a piece of stainless steel mesh and tying it down with thread. Buce Plant recommends a light trim with sharp shears now and then for denser growth, with the filter off so clippings do not spread around the tank.
Carpets that grow better with CO₂
The catalog rates Monte Carlo, Marsilea crenata, micro sword, Helanthium tenellum and Pogostemon helferi as growing better with CO₂. Buce Plant reports Monte Carlo working without injected CO₂ under enough light, so these are possible in a low-tech tank, only slower and less certain.
Dwarf baby tears and Glossostigma are rated as requiring CO₂ and high or medium-to-high light. Leave them for a tank with injected CO₂.
How to plant a low-tech carpet
- Use a nutrient-rich aquarium soil if you can. Buce Plant says a good aquasoil releases nutrients slowly and makes root tabs unnecessary at first; in sand or gravel, add root tabs.
- Plant densely. Split pots or tissue culture cups into small portions and push them in close together across the foreground.
- Keep the light on for 8 to 10 hours a day, as Buce Plant suggests, and keep tall plants from shading the foreground.
- Consider a dry start. Buce Plant calls the dry start method, where plants grow in damp substrate before the tank is filled, one of the best ways to establish a low-tech carpet, because roots develop before the water goes in.
Frequently asked questions
What is the easiest carpet plant without CO₂?
Dwarf sagittaria is rated easy and fast-growing with no added CO₂, and Buce Plant calls it one of the easiest carpeting plants for low-tech tanks.
Can Monte Carlo grow without CO₂?
It can with enough light, according to Buce Plant, but the catalog rates it as growing better with CO₂. Expect slower, thinner growth.
How long does a carpet take without CO₂?
Months rather than weeks for slow plants. Buce Plant gives months for a microsword carpet without CO₂; fast plants such as dwarf sagittaria spread sooner.