Can you run 1.5HP pump with 1HP impeller?

May 25, 2012
Will anything bad happen running a 1.0hp impeller on a 1.5hp motor? Will this indeed slow the flow?

I had to replace the original 1.0hp motor this year and after some research thought a 1.5hp would be better. It was suggested here that the 1.5hp would have several cons and really no pros verse running the same as original 1.0hp. It's a 25K gal IG with 1.5" piping and Hayward S240 sand filter.

I talked to the vendor about an exchange of my 1.5hp to a 1.0 and his suggestion was to run the 1.0hp impeller which would slow the flow. And, in doing so the motor would actually not be working as hard.

My main concern is filter effectiveness. I've been running the pump 24/7 for the last several years (summers only) and will have a timer installed this year. I think even if the 1.5 does use a little more electricity, running less than half the time will net a reduction in costs.

Bama Rambler

Mod Squad
LifeTime Supporter
TFP Expert
Jun 23, 2009
SouthWest Alabama
Putting a 1 hp impeller on a 1½ hp motor essentially makes it a 1 hp pump. The motor will draw alomst the same current as a 1 hp motor and the flow will match a 1 hp pump.
May 25, 2012

I put the 1hp impeller on the new pump last night and all is good. Flow is definitely more controlled, it was really moving with the other impeller.


Well-known member
May 11, 2009
Youngsville NC
Considering the cost of parts on that is around $100 - I think I'll pass. I have an old (low hours) Hayward PowerFlo II 3/4 hp that I just got a strainer assembly for if I really want to try a smaller pump