Fermentations can be deceiving. Look at the apple wine I tried to make yesterday. Fermentation would not start at all. I was lucky to get it going at all.
And see what happens next! When the fermentation finally started I was still a little worried because it remained a little slow. For that reason I decided to put it in the 15 liter demijohn and fill it up. Champagne yeast usually does not create a lot of foam so I did not expect problems.
Only a few hours later the weather changed dramatically. From a relaxed sunny day it turned into a hurricane. Fermentation became quite violent and I was afraid that the air lock would be filled with foam and eventually overflow and spill on the table.
A simple solution is to accept the fact that it overflows and place the demijohn in the shower so you can clean it easily. Perhaps your family will not think that this is a brilliant solution.
And they are right. A nicer solution is the Tsunami airlock. It obviously is not a high tech solution but it works good enough. And it is very easy to make.
Obviously it does not stop the foaming but the foam is collected in the bottle.
Please note that in extreme cases the bottle will be filled, so you still need to check it.
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