How to make beet kvass in Winter? I often make fermented beet kvass.  This was going well in summer, but now in the colder weather the environment is too cold for the kvass to ferment properly.  The home temperature is 60F, but the kvass needs 72F-75F.  

What is the best way to keep the kvass jar warm?  A heating pad with a thermostat?
If you are handy with electrics and electronics, linking a heating element to a PID controller is probably your best bet for stability.

This will give you quite stable temperatures.

You can find many sets of instructions by googling homemade sous vide pid,which is a very similar application, although higher temperature ranges are usually the goal.