Does your pump turn on at night by itself? It is doing so because the computer control has a freeze sensor. when the temperature drops below 36 degrees Fahrenheit, the system will turn on the pump.
This is to prevent water from freezing in the pipes. Generally here in the Bay Area in California we do not have hard freezes (where it stays below freezing all day). In this case the freeze sensor function is not really needed.
That being said, we do install freeze sensor function on all of our new pools. This is because, on rare occasions, there will be a bad freeze, and we do not want equipment damage.
Typically the damage would initially form in the small pipes, in the heater, or other pipes less than 1 inch, but if the freeze was large enough, then the 1 1/2″ and 2″ pipes would freeze also.
The last time we had a hard freeze in this area, was in 1989. for about a week, we had freezing temperatures all day and night. Ice formed on the surface of the water of pools, in some areas, such as Hillsboro, we saw ice thickness of 6 inches or more. this damaged tiles in the pool structure itself. In the equipment, the water froze inside the heat exchanger, and practically all heaters were damaged. It was an expensive repair, and parts became unavailable for many months. It was the summer before everything was repaired.
Many persons with old heaters simply discarded the heaters and bypassed the plumbing. If you have purchased a house and found no heater on the pool, yet a gas line located at the equipment, this is likely the reason.
As a side note this is why you find plumbing “cosy’s” over the city water backflow pipe assembies that extend above ground in public landscape areas. these were all installed after the freeze of 1989. This plumbing is made of copper, not PVC like swimming pools, and so these pipes absorb the surrounding temperature more quickly than in pools.
The pool needs a heater (or solar) to provide a full season of use.
So in this area although we don’t have hard freezes very often, we still activate the freeze sensor, because if a freeze was to happen, and one did not know to start your pump, then your pool could sustain some irritating damage.
Some people find it annoying for the pump to go on unexpectedly in the middle of the night. If that is the case we can easily disable the freeze function on the computer.
For those persons without a computer control, such as an Intellitouch, Easy Touch or other, there is no freeze protection, so if there was ever a big freeze, one should turn on the pump during the time when the air temperature is at freezing or below.