How to prevent airlocks to get soaked out when vegetables soak up water

Question

Fermenting the vegetables in 2,5L glases I always face the problem that the vegetables soak up a lot of water and then dispense a lot and then towards the end soak up even more. The problem is, that the airlocks get soaked out when the volume in the glass diminishes. They are just too short. I use the standard one.

I consider airlock as important. What I did so far is to wait 2-3 days until I fill in the water in the airlocks, but it didn't help a lot. Often the airlock breaks and it soaks in the water from it.

I wonder, whether there is a point in time, when it can't happen anymore, or anything else to know about the stages of fermentation?

Answer 1

Use an S-shaped (aka one piece) airlock instead. Harder to clean, but doesn’t siphon out at negative pressure.

Answer 2

Another way I found is to build something like this:

In the lid I glued a ball valve and used a silicon gasket between lid and glass. So far, I haven't found a thin enough gasket to lock the lid. I guess, it would also be possible to use a duck-tape. A further idea is to insert an overpressure valve. There are fancy connectors between the tube coming from the pump and the glass, but the way I did it here is fine for me.

Here are the parts I used:

As glue, I used epoxy.

What's really important to notice is that you will need a vacuum pump that is suitable for humid air. They are called oil-free or dry-running vacuum pumps, and are actually the only ones suitable for food. On the picture, you see an oil-containing vacuum pump, however. It seems to work if you pump out all air right after preparing the jar. If the fermentation process has started once, there will be released many bubbles when pumping, releasing too much humidity and the oil gets mixed with water and salt, which is very bad for the machine.

As it is not well-engineered, feel free to improve and let us know