Fermentation causes buildup of pressure. Adapting the wine industrys's "air-lock" system a help. This works by restricting the entrance of air and contaminants into the fermenting vessel in much the same manner as the elbow under your sink. Until this upgrade, most people simply covered their container with cheesecloth or tightened the lid litely to protect their ferment from airborne contamination. Frequent "burping" of the container was reguired to avoid possible explosion of jar. This is really not sufficient by todays standard.
We will soon be releasing a new "Waterless Airlock" based on the "umbrella valve"....... This will allow very LOW PROFILE STORAGE or footprint on your countertop!