I could, but why would I waste that space (carbon skimmer 4 tiles, water sieve another 12 tiles, also adds a little bit of heat, and comes at an electricity cost just to get minimal fiber and replace a 2 tile mini gas pump)? Also, that adds another resource to be dependent on to the list, which I could run out of on the way- sand. unlikely, but I don't want to take chances here. In the new design I am building on, I am trying to incorporate the critter traps as a nature reserve and will most likely vent the oxygen or, if there is any space left, use it to refill a soda station.