Low pump flow

Aug 16, 2007
I have a whisperflo 1 1/2 HP pump that used to pump like a charm. The outlet pressure is very low. The pressure gage reads 0 and I confirmed this by opening the valve on the top of the filter housing, and water just trickled out. I have cleaned all of the skimmers and the strainer, and checked the impeller for obstruction. I tried pulling from the drain and from the skimmers and no change. I think that the O-ring on the strainer basket is ok, but can't be sure. There are some small bubbles coming out of the jets, but not that many. The gage used to read somewhere around 5 psi but now is down to 0.

I really think this is a pump performance or inlet restriction problem, but I don't know what to do next. I'm getting algae now so I need to do something. Please help.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
If you are sure you have no restriction on the suction side, check to see if the impellor is tight on the shaft.
Aug 16, 2007
Thanks for the reply. I'm not sure that there is no restriction. Also, I checked the impeller and I'm pretty sure that it's not loose.


TFP Expert
LifeTime Supporter
May 3, 2007
Pleasanton, CA
With a suction restriction, the pump is usually very loud and there is air in the pump basket.

Also, you can try and flush the suction line with a drain king or hose wrapped with a rag.