Why is there condensation on the inside of my CO2 bottle?

NJ Devils Fan

#1 Devils fan
Oct 28, 2002
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On the inside of one of my DiY CO2 bottles, there is condensation. Why is that? There are no leaks anywhere, and just yesterday, I threw out 75% of the mixture in each bottle and added the ingredients again like Faramir said. Yet, there is still no bubbles. Should I just make a new mixture?
 
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