Not sure how long to run you filtration system? The filtration system should run long enough to filter all the pool water at least once. A good rule of thumb is filtering your pool water two times a day.
Here is how you calculate your filtration time:
1) Calculate the gallons of water in your pool
2) Find out the flow rate for your pool pump in gallons per minute
3) Divide the gallons by the flow rate; this will give you the number of minutes you need in order for all the water to filter through the pump.
4) Divide the minutes by 60 to get how many hours.
5) Then multiply the hours by two to ensure filtration is completed two times.
For Example: if you have a 5,000 gallon pool and a pump rate of 25 gallons per minute, it will take 200 minutes which is about 3 hrs. 20 minutes. Then multiply by 2 and you will see you will need to run your filtration system about 6 hrs. 40 minutes a day.