For cost and complexity reasons, I can't simply use a thermowell or tape the thermometer to my carboys because I ferment multiple beers at once. Right now I have my first beer that is fermenting so actively that I needed to make a blow off tube.
I've read that the temperature inside the carboys can be from 5-10 degrees warmer than the ambient temperature, so I set my freezer to 58F (14.4C) and plan to crank it up slowly to 65F over the next few days. Should I go lower in the future?
Also, while I'm on this topic, as I said this is my first time that we've used a blowoff for overflow. We have it overflowing into about a gallon of sanitizer (water/starsan mixture) and the water has turned a murky brown. Should we clean this daily or is there no risk associated with this?