A friend’s aarke Carbonator Pro failed. It was venting air somewhere between the canister and the bottle, therefore the bottle of water wasn’t receiving carbonation. The Carbonator Pro was defective.

If you reach out to aarke they are very nice. But no matter how thoroughly you explain the situation, they will provide first-tier boiler plate customer service responses. You will say it is not receiving carbonation or that it is venting air, and they will tell you it is likely the interior gasket has failed; it’s apparently a common problem. The Carbonator Pro comes with one gasket cleverly concealed under the base of the unit. They will instruct you to replace the interior gasket with the replacement gasket. They even provide a private video that demonstrates the replacement process – it only takes a few minutes.

But that’s not this problem.

This one is tricky. I’ll try and explain: where you push down on the button, if you could imagine there is a chamber underneath there (we’ll see it momentarily). If you can imagine air venting in that chamber – that was this issue. It wasn’t venting air at the canister per se; the canister was making a ‘good seal’ with the unit. But *then* the air was venting, underneath the button.

So let’s get under there!

The first thing you want to do is remove this screw – these are T10s btw:

Once you remove that screw, you can pull that top ring part directly up, revealing the chamber compartment underneath.

Then, you will want to remove the 4, smaller (also T10) screws around the perimeter of the compartment. (The larger screws are T20, so your T10 screwdriver won’t fit and there’s no need to remove those.)

The four smaller, perimeter screws can be seen in the first of these three images:

One you have that top piece of plastic removed, you will see a bright white piece of plastic below. This is the button mechanism (the large silver ‘button’ is superficial). Lift both of these two pieces of white plastic up, and below you will see the top of a piece of brass surrounded by a spring (note: the spring may actually cause the whole thing to ‘jump up’ – possibly even with enough force to leave your workbench!). This brass piece is the culprit:

Or rather the black O-ring on/around the brass piece is the culprit!

You can see here it has some wear-n-tear, and was in fact sheared through, torn:

Once you replace that part you’ll be good to go. Because the ring is sheared it took me some time to measure it, and properly source a replacement. Truth be told I’m not entirely satisfied with my curent replacement part, but the Carbonator Pro does absolutely now work! So that’s all that really matters. My dissatisfaction with the current part is that it is ever-so-slightly ‘loose’ on the brass part. It slides up and down a tad bit, which even the broken ring didn’t do. I suspect this is because the replacement ring should be about 0.5mm thicker than the one I sourced. With that knowledge in mind, the replacement rubber ring I sourced had a 7mm outer diameter (OD), 4mm inner diameter (ID), and a 2mm thickness. (Again I suspect the thickness *should be* 2.3-2.5mm for a proper, snug fit on the brass part)

This was truly a tricky fix. Not your usual reported issues (e.g. here, here). The Pro is nice, but bulky, so it’s pretty clear why aarke quickly moved on to the Carbonator II design; that said that model is still plagued with issues and the company commonly resorts to the same ‘replace the gasket’ troubleshooting – e.g. here, here. Even then the Carbonator II could have the same O-ring issue, seen here. (One user even 3D-designed and printed a valve replacement part – wow!) Which says there are some central design flaws to that O-ring. I suspect it fails given the amount of pressure the mechanism is under. The interior gasket usually fails or shreds sooner, but there’s always a possibility it’s this O-ring instead, and so I hope this guide helps anyone who is attempting to troubleshoot an aarke Carbonator Pro. I myself have now saved a $300 appliance from the landfill and learned a ton about troubleshooting carbonation machines.

Oh and just a quick shoutout to Dr. Lyons at Psychology Info who has written a remarkable post about modifying the Carbonator 3 with a larger CO2 tank – that’s awesome!