Episode 3 of Season 3 is a stream that picks up the BasketCase3 colony with the two water tanks from Episode 2, the clean one and the polluted one. The first half fixes problems: air pressure on the farm floor, food with nowhere cold to go, and more polluted water than the colony can clean. The second half starts something new, sealed rooms for Electrolyzers to make oxygen. When the video ends, fourteen duplicants are alive, the rooms are half built, and "Insufficient oxygen generation" is still in the alerts.
Pressure on the farm floor
The stream opens on the tanks. "So we have our current water tank that we're working on with a little bit of polluted water inside of it." The pump that should move the water reads "Pipe Blocked," and the plants up on the farm floor are not happy. The commentary first guesses the air pressure there is too high, then checks again: "it's actually too low. Oh okay, so stop that, disable building. I'm actually pulling out too much oxygen." The gas pump from Episode 2 is switched off, and a few minutes later "these plants are actually also now happier too." Food gets priority 6, "just so it's a little bit above default."
Refrigerators and more distillers
Refrigerators are ready, so a couple go in on solid ground, get power, and take the food that was sitting in an unrefrigerated box. The old ration box comes out later. A Fertilizer Synthesizer, which uses polluted water, is passed over for now, because the colony can already turn polluted water "straight into regular water."
With duplicants standing idle, two more Water Distillers go in. Then a pocket of polluted water nearby gets a pump of its own, a liquid bridge, and a corridor so the duplicants can reach it. Soon "we have more polluted water pumping in than we're able to process," so the outflow gets two outlets instead of one. More beds go down too, "temporarily in a really weird spot."
Planning the oxygen rooms
The colony still is not making enough oxygen. The Electrolyzer, in its tooltip's words, "produces oxygen and hydrogen using water," and the plan is a small room for each one: "it's going to be airlock door followed by an air pump." That needs doors that block gas, so research comes back after a long break. Decontamination is picked, which brings the Mechanized Airlock and an ore scrubber.
A new duplicant is ready to print. The choice is Ruby, a miner, since "I'm doing a lot of digging right now." More refrigerators go in as well, because "my crops are doing so well."
Building the Electrolyzers
The Electrolyzers go in a row of small rooms, each with an air pump. They are kept switched off until the rooms are done, so the hydrogen does not drift away. Once the research finishes, the airlocks get power, a water pipe runs in, and gas pipes and a Gas Filter go up, which "has to be built in open space." The layout changes halfway through: the gas pipes are torn out and run down instead of up, and the plan becomes filtering out the hydrogen first.
Where it ends
The last thing on screen is the Power menu. The Hydrogen Generator "produces power. It doesn't produce any pollution," the commentary reads, and two are placed in the power overlay. Then the video cuts to the end card, with the rooms still unfinished.