Does it hurt to turn off the aerator from time to time for three or 4 days in an effort to save electricity?

We don’t recommend that.  The purpose of the aerator is to help keep the bacterial colonies thriving and we also recommend running your aerator on a continuous mode.  The yearly cost of running an aerator continuously, varies from state to state so depending on what region of the country you live in and the average retail price of your electricity provider you can expect to pay in the range of $58.78 - $217.25