Freezing temperatures & Pool Equipment generally do not mix well. If the water in your equipment is not moving, it will freeze at 32degrees. Most pool equipment systems have freeze guards. Basically, a freeze guard is a sensor that tells the equipment system to turn on at a certain temperature. Most are around 36 degrees.
For a hard freeze or snow, here is one extra precaution you can take to help the pool water from freezing and causing costly damage to your equipment. Cover your equipment with blankets (any old comforters or thick blankets). Make sure NOT to cover the exhaust of the heater, some systems have the heater come on in cold weather. DO cover all pipes, pumps, & filters. You want to create a cocoon of sorts over the equipment, trapping the warmth from the ground & the warmth off the motors.
Be prepared for Winter. I have seen this precaution save pool owners thousands of dollars in costly repairs.