Blow off Tube Technique:
First of all, you need to take a drill machine and drill a hole in rubber stopper. Make sure it is smaller than the overall diameter of tubing. After that, insert the tubing into the rubber stopper and also make sure an inch of the tubing protrudes are into fermentation vessel or pot.
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Now put the rubber stopper and tubing assembly in the vessel. You need to check that tube should end in air space and if it is not, then pull and adjust it accordingly. Then take the water and fill it into a glass (half way). Now put the other end of tubing into the glass.
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Take a balloon and make a hole in its bottom by using a straight pin. After that, stretch this balloon exactly over the neck of the fermentation pot or vessel.
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As soon as the fermentation starts, you will see that CO2 will inflate the balloon. However, the hole in the bottom of the balloon will prevent the growth of pressure. The airlock is complete now and the oxygen does not have access into the vessel while carbon dioxide will escape easily.
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