Longer stays in an underwater station require systems to filter out Carbon Dioxide (CO2) from the air that is exhaled by the aquanauts. These CO2 scrubbers generally consist of a fan that pulls air through a canister filled with Carbon Dioxide (CO2) adsorbent, such as Sodasorb or Sodalime. To get a rough idea about CO2 scrubbers and their prices visit the webpage of AMRON International.