Base design is important. You need enough space in each room for items, and decor, while enough space between rooms to allow for airflow (thus needing less O2 producing items.) Creating a 3 block space between rooms. Room 1 ends, empty tile, ladder, empty tile, room 2. Dupes can jump one space, land on the ladder, and go to the next room. Having a 3 open block space between rooms provides better air flow for Oxygen. - Refer to the Image section below. Algae is Limited Early Game Early game, Algae is limited. Move on to Electrolyzers for O2 until you can SAFETLY enter the Slime biome.