I would think that 2-3 days is not enough for proper carbonation, Personally I do 10-12 PSI for 9-14 days and dont have problems. That is in a 40 Degree freezer.
Not trying to derail the thread or start an argument but how does glass introduce more risk... At worst glass and plastic are equal in fermentation with proper care and handling..
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Are you accounting for the water in the herms Coil when doing water Calculations? Depending on length of lines and the herms coil itself I could see maybe thinking that the grains have swollen when in reality the water has been moved.