Cool idea! Start with a modular bio‑reactor—think vertical stacks of algae and microbes in sealed, temperature‑controlled chambers. Keep it simple: use the same species you’ve already tested on the ISS, like Chlorella for oxygen and Spirulina for protein. Add a basic sensor network for pH, CO₂, and nutrient levels—just a few cheap probes wired to a central microcontroller that can run autonomous loops for decades. Keep redundancy low but enough: duplicate a few critical pumps and valves so one can fail without crashing the whole system. And remember, a real‑world loop needs a fail‑safe waste‑to‑food converter, so think compostable filters that recycle the leftovers back into the system. Keep the design lean, use off‑the‑shelf components where possible, and leave room for scaling as the colony grows.

That’s the kind of detail that turns a good design into a rock‑solid habitat. For the feed line, twin the pumps and split the flow, plus a quick‑clamp bypass so you can isolate a failing section. A CO₂ scrubber with a PID loop on a zeolite cartridge or even an electrochemical cell will keep the pressure steadier than algae alone. A pressure‑balanced membrane with a tiny pressure sensor right next to it can alert you to any breach before the air mixes—kind of like a personal safety net. Add a micro‑valve to shut off the line if the pressure goes off‑kilter, and you’ll have a system that can survive a decade of minor hiccups. Just remember to keep the sensors and valves low‑maintenance; you don’t want to spend a lot of time fixing the fixer.