Pump and motor size

H23

Member
May 19, 2007
9
Ohio
I"m installing a 10,000 gal. AG pool. I upgraded to a 21" sand filter (Pentair T-210WF-H) Max flow rate 43.6 gpm. Also a Sta-Rite pump (JWPAS5F-A4). The plaque on the motor reads; HP 1.5 SPL, 115v, 3450 RPM S.F., Max 12 amp. The sticker on the bottom of the motor reads; HP 1 or 1.5 SPL. So is this a 1 hp or 1.5 hp motor. Also there is not a chart or any information about how many GPM this pump will pump. Any information would be greatly appreciated.

Mike
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
The manual is here, but I don't see any flow rate curves.

HP alone doesn't tell you everything, you also need to know the service factor (SF). You multiply the HP by the SF to get the brake horsepower, which is what actually gets applied to the water. It's all a morass of different standards and deciptive marketing. See WikiPedia for some background. Some manufacturers sell motors of various HP that are actually all the same motor, just with different SF. One way to interpret what your label is saying is that it is a 1 HP motor with a service factor of 1.5, so 1.5 brake HP, but that might not be right.

In any case that pump is probably a bit much for an above ground 10K gal pool. I expect that you could easily get away with a 1/2 HP motor. A larger filter is always better but a larger motor costs more to operate. If you don't have something to do with all that water movement (spa, fountain, waterfall, etc) there isn't much point in getting a big motor. I have a 20K gal in-ground pool and get along just fine with a 3/4 HP motor.
 

H23

Member
May 19, 2007
9
Ohio
Will a smaller pump

Will a smaller pump 1/2 HP have to work harder with a larger sand filter or does it make any difference. What about a 2 speed pump, could it be ran on low or would it be to hard on the motor. Also there are no number after the S.F. on the nameplate.

Thanks,
Mike
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
No, a smaller pump wouldn't need to work harder with a larger filter. The smaller pump would move less water than the larger pump, but still plenty of water for normal keeping the water clean purposes. Larger filters have less resistance to flow than smaller filters and they need to be backwashed/cleaned less often. A larger filter is always better. The only disadvantages are price and physical size.

A two speed pump would be fine. I am not sure why you would need one, but it would work just fine.