Infinite storage of polluted water geyser

[beeper]

I have a polluted water geyser that outputs at 15 kg/s during an eruption with an average active output of 6 kg/s. This means a single pump and sieve cannot keep up unless I build a lot of excess storage. It seems like a perfect time to try out some sort of infinite liquid storage. I was thinking a door compressor/pump, but this setup with two gasses seems within my grasp:

The problem is I don't understand how off gassing of the polluted water works. Does the box around the geyser need to have extra height to let the off gassed pO2 go someplace and allow the polluted water to get to the pump? Is it possible to prevent off gassing?

[mathmanican]

4 hours ago, beeper said:

The problem is I don't understand how off gassing of the polluted water works.

If you let PO2 be the bottom gas, then once it passes 2kg, you won't have anymore off gassing. So just put hydrogen or something else above the PO2, and you can use that build. You can also use something like this.