Is this base recoverable?

[Zekava]

Needless to say, this is my first time playing with very little prior knowledge. This is my first base, and I know I did a whole slew of things wrong, but I feel like I'm just missing something here. The slime->algae converters have been running for a long time, and I have tons of algae farms, but the oxygen content is continuously going down, despite my efforts. I have a lot of low priority projects that were basically there to keep them busy if they weren't doing anything.

I feel like I should just scrap this and try again. From the little reading I've done, it seems like the game has no equivalent of the first law of thermodynamics, so it seems hopeless anyway, and having 13 people consuming oxygen and food seems like a horrible idea when resources are scarce and limited.

Is there no way to stabilize an ecosystem anyway? Is there no such thing as a self-sustaining base? Is the goal of the game to simply survive as long as possible before dying horribly? What me do?

Ignore all the 0s in the top right, that's a product of me loading the game and keeping it paused. It hasn't updated those values yet.

Edit: additionally, where are the save files located, in case I want to back up this base so I can start a new one without worry?

[2number9s]

Try making a drawing/blueprint of a base.

With tiles and doors to make rooms dedicated to one task

Use the lights, paintings and statues to prevent stress.

oni saves in {documents folder}\oxygen not included\

Also explore the forums for tips and tricks.

[heckubis]

you need more room for clean air to move to rooms you use.  the dangerous gasses will float or sink and contaminated will not kill you only         - decor and chance of disease is the only thing you really need worry about from it.

[heckubis]

the big killer is carbon/chlorine flooding and starvation

[heckubis]

and there is a save as in the esc menu

[SpoonsOnMyElbows]

The distillers are not worth it. They produce such a tiny amount of slime that it might buy you a second of air for 1 dupe.
If you have electrolyzers researched, you probably want to build those. They use water, but then distillers use much more anyway.
Also, you need to get rid of the bad gasses too. There are ways to remove them with broken game mechanics, but if you are not a fan of using that kind of thing, then use a scrubber.
1 thing to remember is that hydrogen and dirty oxygen will rise above oxygen, and CO2 will drop below it.
Make sure there is space for the gasses to flow like this, and not pocket up into unbreathable death zones.
Because of this, you would put your oxygen cleaners higher up, and your scrubbers low down.

Also, contaminated oxygen is not the end of the world. Your dupes can still breathe it just fine, although it will make them sick (which they can't die from) and stress out.
Currently, the only way to be fully sustainable is to use broken game mechanics.
I posted a thread of a fully sustainable base an hour or so ago, but if you want to play the game as it's intended, it's not for you.

As far as oxygen goes, you can be sustainable without abusing game mechanics.
There are creatures called MORBS that produce contaminated oxygen.
You can "spawn" them by killing one of your dupes, or find them randomly around the map. They will spawn eventually around the body (up to 3 per game session).
They are friendly mobs, and will "fart" out breathable contaminated oxygen.
 

[Sarig]

A few things come to mind:

Clutter.  They hate this.  Click the Decor overlay and mouseover the debris at their beds.  I think it's -10 decor per object.  Sweep that area.  Tiles on the floor and ceiling will add a little decor.  If possible, add a few ceiling lights.  At minimum, add at least 6 paintings spaced out above the beds.  Maybe one or two at the mess tables.  Wherever they spend a lot of time.

In the bottom right area where you have queued up a pump, I would just take out that entire section.  Making a large pit will buy you some time to deal with CO2.  Add a couple gas permeable tiles, or at least 1 square sized holes, on every level so gas can resettle.  Gas movement is very slow so give it some time.

One last thing.  More duplicants make the game much harder.  It might be too late to do anything about it now but for future reference I find that 5 or 6 is plenty.

Good luck.