See so many recommendations - PB says 1 time in 24 hours. Online resources range from 1 to 4 times in 24 hours. I have a VFD pump. 13,500 gallons. Figure to run in from 7am - 10:30am at 50GPM (10,500 gallons) and again from 2pm-5pm at 50gpm (9000 gallons). How does this sound? This of course is independent of any swim time where bubblers, hot tub, etc. etc. will be utilized circulating more water. One a normal day, is 19,500 gallons in a 10 hour window sufficient for a 13,500 gallon pool? Thanks!