Does Running the Pump Cool the Pool Water?


LifeTime Supporter
Aug 13, 2007
Our pump puts out a pretty good swirl in our small pool.
So we wonder if it cools the water, when run during the day?
We don't need it to be cooled. Brrrr.
We're having a lovely summer, but not a lovely summer for swimming, most days.


LifeTime Supporter
May 10, 2007
Baton Rouge, LA
hmm.... good question.

With no scientific backing... I think if I wanted to warm my pool, if I could get away with it, I'd do my pump cycle at night... and let the sun try to warm the water during the day.

Seems to me that the temp would increase the most without circulation... kinda like us sitting around in the sun without a fan blowing or a breeze. :grrrr:

Good luck!!



TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
The pump has very little effect on water temperature, other than mixing deep water with water higher up. To a small extent running the pump can increase surface agitation, which can increase evaporation, but the effect would normally be very small.

Of course, if you have solar panels it is an entirely different story. Solar panels heat during the day and cool at night.


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
My guess is that if you want warmer water, run the pump all the time. My reasoning is that if you don't run the pump, the surface water will be warmer than the rest of the pool. This will result in more heat loss when the air is cooler (at night), and less heat gain when the air is warmer (during the day) since heat transfer increases with temperature difference.


LifeTime Supporter
Aug 13, 2007
Thank you.
We've been working on Steve's theory.
Our air temp has not, necessarily, been much warmer than our pool water.
Then add the 10-12 mph breeze, cloudy and you've got a dang
chilly swim, for me :-D