Algae Terrarium

The Algae Terrarium is a power-free oxygen production building that uses Algae and Water to generate Oxygen while also consuming Carbon Dioxide. It is more efficient at converting its input resources than the Oxygen Diffuser or Electrolyzer, but each individual terrarium produces oxygen slowly, so it is not a space-efficient long-term source by itself.

Its biggest advantage is that it can be set up very early without any power infrastructure, making it useful for temporary oxygen production or for extending a colony into remote areas before Atmo Suits are available. It also consumes Carbon Dioxide, which can make it helpful in cramped early colonies where air control matters. On the other hand, it creates a steady stream of Polluted Water and still requires Water and Algae to be supplied, so it only remains convenient if those logistics are handled well.

Practical notes:

• One Algae Terrarium supports about 0.4 Duplicants, so a colony needs multiple terrariums to sustain several Duplicants.
• It consumes only 0.3 g/s of Carbon Dioxide, so it is a minor carbon sink compared with dedicated cleanup buildings.
• With proper Polluted Water recycling, its Water-to-Oxygen ratio is roughly 1:4, giving strong resource efficiency compared to the Electrolyzer.
• The output Polluted Water must be removed manually unless a delivery and collection setup is built around it.
• Water input can be automated by letting Water drip onto the floor through a Liquid Vent, allowing the terrarium to draw it in.
• Algae delivery can be automated with Auto-Sweepers.
• A single terrarium must be plumbed manually every 360 kg of stored Polluted Water.
• One Water Sieve can recycle the output of about 17.2 Algae Terrariums.
• If the input Water contains germs, the produced Oxygen will be infected, but the Polluted Water output will not carry germs.
• Lighting from Floor Lamps, Shine Bugs, the Printing Pod, or Ceiling Lights increases Oxygen production by 10%.
• Placing terrariums near Water sources and nearby Polluted Water storage reduces hauling time and makes them easier to manage.

Because they generate a lot of Polluted Water for the amount of Oxygen they produce, Algae Terrariums work best as an early-game bridge or as part of a carefully planned recycling loop rather than as a colony’s final oxygen solution.