I tapped into my wife's sewing skills to make an insulation pouch that gets tied onto a bucket/carboy and has a pocket to place my controller temperature sensor & a reference thermometer if desired. The ceramic fiber insulation is in a freezer zip-lock bag. The dual strings really convince me the probe is held close to the bucket for a good reading of the water temperature. Pics below:
Insulation Pack for Temperature Control Sensor
Linear Mode
