Optimum time of day and length of time to run pool filter pump?


Minister of Fire
Feb 1, 2010
Salem NH
When do you run your pool filter?
I am trying to find the best time to run thepool filter with timer.
They say 2 cycles of water change is minimum for 1 day.
So you take the gallons from a pool water https://www.orcity.org/sites/default/files/swimming_pool_water_estimator.pdf
This 18 ‘ round 52” high pool is 16,600 gallons
Divide by the filter pump flow rate, so for my Haywood 1.0 HP motor and 2” hose about 52 GPM which is 3,120 GPH
16,600/3,120 = 5.32 hours for 1 cycle and 10.64 hours for 2 cycles so at least 11 hours per day and the more night time hours when electric rates are low the better, but should be on when the pool is in use. Since we swim mostly after work then
4 pm to 3 am in the morning may be a good plan?
On weekends if we swim earlier then I can flip the lever to on earlier in the day. :)
Any comments?


Last edited:


Feeling the Heat
Nov 16, 2009
Cambridge Springs, PA
Ideally you want it to run during the period of use plus a turnover so your 4pm to 3am sounds good.

Since you just filled the pool something to keep in mind is to not use the di/trichlor tablets all the time. Use them until you get to the proper stabilizer level then switch to plain old pool chlorine.

Reasoning is you can get too much stabilizer present in the water and end up needing more chlorine than necessary.

If you haven't found it yet https://www.troublefreepool.com/blog/ is a great resource with calculators and a forum just for pool stuff.

I'd also suggest springing on a nice test kit. This is the one I use and will do everything you need.
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Minister of Fire
Oct 20, 2018
Please also give consideration to where the pump is, how much noise it makes, and if neighbors can hear it. Our neighbor's loud pool pump is really annoying.
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Minister of Fire
Nov 23, 2005
my pool is 12 by 18 i figured out some time ago that 5 hours did well so i just added a hour. crystal clear.
i run it between 7 pm and 1 am for some stupid reason when people are in the pool and pump is running sometimes the flapper on the skimmer shuts and stays shut making the pump run dry. i also run it with the sun down because the sun eats up the clorine
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