Why is my pump losing prime?

Drew80

0
Feb 26, 2013
337
Austin, TX
This is a recent thing. All of a sudden my pump can't seem to keep prime. I made sure that the lid is on securely, the basket and skimmer are both clear, and my filter is clean. Am I looking at a suction side plumbing leak?
 
This is a recent thing. All of a sudden my pump can't seem to keep prime. I made sure that the lid is on securely, the basket and skimmer are both clear, and my filter is clean. Am I looking at a suction side plumbing leak?
Most likely, yes.

Have you tried lubing the pump lid o-ring? The drain plug o-rings?

Is the water level half way up the skimmer?

The other possibility is an impeller clog. Did this start after vacuuming up a bunch of debris?

 
Start with the basics:
- Pump lid (and drain plugs) have O-rings lubed really well
- Pool water level at proper height
- Skimmer weir door not stuck or closed
- 3-way valves before the pump didn't get partially closed by mistake

You can also post a pic of your pool and that might give us more to go on.
 
Drew,

Tell us why you think the pump is not hold a prime.. What actually happens..

When you shut off the pump, does the pump basket water drain back into the pool, or does the basket stay full of water?

Thanks,

Jim R.
 
Drew,

Tell us why you think the pump is not hold a prime.. What actually happens..

When you shut off the pump, does the pump basket water drain back into the pool, or does the basket stay full of water?

Thanks,

Jim R.
The pump water level is dropping about half way down during operation. I run my pump constantly so I haven't tried turning it off and letting it sit. I'll report back.
 
Most likely, yes.

Have you tried lubing the pump lid o-ring? The drain plug o-rings?

Is the water level half way up the skimmer?

The other possibility is an impeller clog. Did this start after vacuuming up a bunch of debris?

I haven't lubed either - I'll try that.
Water level is fine.
I haven't vacuumed anything. I have had a lot of debris in the pool lately, but the big stuff would have gotten caught in the baskets. Wouldn't an impeller clog cause water to stop flowing?
 
Wouldn't an impeller clog cause water to stop flowing?
It may not completely stop flowing but the filter pressure would drop too which is a sign of a suction side clog, impeller or line.

But if water is flowing, then technically, the pump did not lose prime. Still may be an air leak though.
 
I should add that this only happens at low speed. When I run the pump at full speed it blows all the air out of the line and it doesn't return.
VSPs often see a small drop or air gap in the pump basket over time, so increasing rpms is common once or twice a day. But if you are dropping halfway down in the basket, it may be more. Be sure to lube those O-rings and while your at it, if it's been a while, be sure the filter carts are clean and not resulting in a bit of resistance or back-pressure from the filter.
 

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When you turn off the pump after it's been on high speed, do you hear a gurgling sound and water draining back from the equipment into the pool via the suction line? If so, you may have an air leak somewhere on the equipment pad (filter/valve/pump/etc). Sounds counter-intuitive but I had the same issue and it was an air leak in the MPV that didn't leak water when it was turned on (something to do with the gasket, I imagine).
 
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Is it typical to run for a few minutes a day on high?

Drew,

Not sure it is typical, but it is something that I do and makes sense to me. It seems that all VS pumps have some bubbles under the lid at low speeds. I can see where is would not take very much of an air leak to allow these bubbles to get bigger and bigger over several days. Ramping up the speed for just a few minutes each day eliminates me having to worry about it at all.

Thanks,

Jim R.
 
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