Vacuum losing suction

[JimmyGee]

20x40 IG vinyl liner 36,000 gallon 20+ year old pool. Had a number of issues this year opening the pool (plus some vacation travel) and my pool is just about ready, but needs a good vacuum. Once connected, the vacuum will lose its head.

Replaced the pump motor with an exact replacement (1.5hp). Rebuilt the pump. Purchased a new vacuum hose. Still no luck. When the vacuum hose is disconnected from the skimmer, or suction side is diverted to the bottom drain, all works as it should.

I am getting a little air entering at the skimmer cuff - wrapped it with stretch wrap - but to no avail. I’m now adding water to raise the level above the top of the cuff and will try again. In the meantime - any other suggestions?

 

[Rancho Cost-a-Lotta]

I’m now adding water to raise the level above the top of the cuff and will try again.

I bet stopping the air leak will solve your problem. Are you connecting the hose to an adapter plate or directly to a suction port at the bottom of the skimmer?

 

[1poolman1]

You have found the most likely issue, air entering at the hose. Be sure the rotating cuff on the end of the hose is connected to the vac-head.

 

[JimmyGee]

Yes, air. From somewhere. Added water to the pool so the skimmer was practically full. All seems fine with suction at the bottom drain or the skimmer (though when I open the bleed valve at the top of the filter there is a surprising amount of air coming out). As soon as I connect the vacuum I lose the head. The hose is brand new (swivel connected to vacuum). There is a small leak at the shaft seal of the pump, but since it’s leaking water (pressure side?) I don’t think that’s it. There’s one connection between the pool piping and the pump. I’ve wrapped it with stretch wrap as a precaution. 20+ years I’ve never had this happen. I did replace the pump motor this year - it’s almost as if it’s powerful enough to run the system under normal circumstances - but the additional force to pull water thru the 48’ hose is more than the pump can handle, even if I try to vacuum to waste (it’s a Century 1-1/2 hp motor C48L2N134C1, which is what it replaced). My next step is to replace the shaft seal - needs to be done anyway - but I am at a complete loss. Appreciate any/all suggestions.