Oxygen Not Included Wiki

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Oxygen Not Included Wiki
This article has not been revised for the current version (U40-494396). It was last updated for RP-381414. It may contain inaccuracies.
This article has not been revised for the current version (U40-494396). It was last updated for RP-381414. It may contain inaccuracies.

Algae Terrarium is used to produce Oxygen and remove a small amount of Carbon Dioxide (CO2 is not required to produce Oxygen). The Terrarium needs to be supplied Algae and Water to function, and Polluted Water has to be removed periodically.

Algae Terrariums do not have a maximum pressure and will continue to function as long as water and Algae are available.

All resources output have a temperature of 30°C (or higher if the inputs were hotter).


Algae Terrariums provide better conversion rates than the Oxygen Diffuser or Electrolyzer (with algae and water, respectively) and do not require power. However, their water inputs and outputs has to be dealt with manually or by some indirect means. Water delivery can be automated by dumping it on the floor through a vent, and Algae delivery can be automated using Auto-Sweepers. However, expulsion of Polluted Water must be done manually. Algae Terrariums have slow individual oxygen generation rate, which makes them space-inefficient.


  • One Algae Terrarium is capable of supporting 0.4 Duplicants. That is, you will need 5 terrariums per each pair of Duplicants.
  • Each Algae Terrarium consumes only 0.3 g/s of CO2. So for the purposes of scrubbing, 7 terrariums are required per each pair of Duplicant. While Terrarium are convenient, Carbon Skimmers are one thousand times more efficient at this task. For context, it takes 2.5 Cycles for this to clear the Carbon Dioxide generated from 1 second of a Petroleum Generator.
  • Duplicants need to plunger the terrarium for every 360kg of polluted water stored in it.
  • With proper Polluted Water recycling, the water to oxygen ratio of the Algae Terrarium is 1 to 4. That means you get a 400% return in oxygen on water spent. 300 g/s of water used, 290 g/s of polluted water returned = 10 g/s of water consumed to provide 40 g/s of oxygen. By comparison, the Electrolyzer converts water to oxygen only at the rate of ~90%.
    • However, this is misleading as the 30g/s of Algae would have produced ~27g/s of Oxygen while consuming 0 water with an Oxygen Diffuser. So, the actual conversion is 40-27 = 13g/s of Oxygen per 10 g/s of Water, or a 130% conversion.
  • One Water Sieve can recycle the output of ~17.2 Algae Terrariums.
  • Comparison to other methods of oxygen production can be found at Converting Algae to Oxygen.


  • Floor Lamps, Shine Bugs, the Printing Pod, and Ceiling Lights can illuminate Algae Terrariums, causing them to produce 10% more Oxygen.
  • It can be useful for creating an air-pocket in remote areas before an Atmo Suit is available, since they do not require power.
  • Algae Terrariums consume large amounts of Water and produce large amounts of Polluted Water. Placing them near water sources and building a polluted water reservoir nearby will reduce the amount of time Duplicants spend transporting liquid.
    • Early reliance on Terrariums can prove disastrous to a colony's fresh water supply. The Oxygen Diffuser offers easy algae-based Oxygen production if a solution to the Polluted Water is not available.
    • Algae Terrariums can draw water from the environment when algae is supplied, so it is possible to automate water intake with Liquid Valves and Liquid Vents that slowly drip clean water on the floor.
  • The Bottled Polluted Water that is output can be separated with mechanized doors - so as not to interfere with oxygen generation - and left to emit Polluted Oxygen near Deodorizers. See example designs.
    • This method of deodorising the off-gassed Polluted Oxygen is a good source of Clay for Ceramic production.
  • If Polluted Water itself is sought, Algae terrariums can generate nearly 400kg per cycle per duplicant (but consume over 400kg of water while they're at it).
  • if the water taken into an Algae Terrarium has germs, the oxygen produced will be infected, however the produced polluted water will have no germs. The polluted water can then be run through a sieve to reclaim germ free water.

See Also[]