Pump Basket has air trapped - most of the time.

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Woody007

Well-known member
Aug 20, 2020
228
Midwest US
New VSF3 pump and most of the time it has an inch or two of churning air in the basket. Slower speeds are worse, higher speeds slightly better. When I use my booster pump, the main pump clears of all air and looks normal. A few hours after turning off booster pump the air returns in the pump basket, even with the same speed setting.
If I lower the flow rate down to ~25 GPM it will get enough air that it starts spitting it out the returns.
Pretty confident that no leaks in the suction lines since it looks good when the basket is full when using the booster. Not a bubble comes in.

Is it possible restriction in return lines is too much? Wouldn't seem like that would be an issue running the pump at low GPM which makes the air worse.
What am I not understanding about the air in the basket?
 
Read Pump Basics - Further Reading

Restrictions in return lines do not cause air in basket that clears at higher speeds.

It may all be normal for your equipment setup.

Show us pictures of your equipment pad and pumps.
 
Air leaks are usually dependent on flow rate and the amount of vacuum there is within the pump basket.

You cannot assume that because you don't have a leak under one condition, that it won't occur under another condition. The seals in a pool plumbing system are very dynamic and sometimes leaks can be worse at higher RPM/GPM or visa versa. It just depends on the type of leak and where it occurs.

What is your pump make/model# and what RPM are you operating at for the above conditions especially when running the booster?

The booster will increase flow rates throughout the plumbing and increase the vacuum in the pump basket and that may be enough to temporarily seal a leak in the pump basket.

I would check the pump lid and drain plug gaskets for cracks and lube them well with pool lube. If that does not work, then move on to any o-rings you might have on the suction side of the pump.
 
ajw22 said:
Restrictions in return lines do not cause air in basket that clears at higher speeds.
Click to expand...
Just to clarify, the pump basket doesn't clear at higher speeds, it just gets worse at lower speeds.
At ~45gpm there is an inch or more of air churning in the basket. If I go down to ~30 it will get much more air in the pot.
This is a new VSF3 replacing a single speed Challenger. Old pump never had air in the basket.
 
Woody007 said:
Just to clarify, the pump basket doesn't clear at higher speeds, it just gets worse at lower speeds.
At ~45gpm there is an inch or more of air churning in the basket. If I go down to ~30 it will get much more air in the pot.
This is a new VSF3 replacing a single speed Challenger. Old pump never had air in the basket.
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Run at full speed and see if the air disappears.
 
mas985 said:
Run at full speed and see if the air disappears.
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It doesn't go away at full speed. The only time I've seen it be full is when I have the booster pump running with the cleaner. It looks perfectly normal at that point. When I turn off the booster and take the cleaner out the pot starts to get air back in it over a few hours.
FWIW I see a fair amount of air coming out of the tail on the 280 for the first few minutes of running. I suppose that could be the air that was in the pot.
 
What is the make/model of the new pump?

What is the RPM when running the booster?

What is the filter pressure when running on full speed with and without the booster?

The booster should not be making that much of a difference unless you are running at very low RPM.
 
mas985 said:
What is the make/model of the new pump? Pentair VSF 3

What is the RPM when running the booster? 3K

What is the filter pressure when running on full speed with and without the booster? 20 PSI same with or without booster

The booster should not be making that much of a difference unless you are running at very low RPM. I know. That's why I'm having a hard time understanding why it makes any difference at all. I can hear the air in the booster for the first few moments when it starts and see bubbles coming out of the 280 tail.
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mas985 said:
I think the booster is a clue, not part of the problem. I'm just not sure what it's trying to tell me. It's almost like the pump can't expel the air from the basket on its own but somehow the booster helps to draw it out. It's a separate line from the booster to the pool. Is there any way the pump could be too large for the 1.5" lines? It wouldn't seem that would matter especially lower the flow rate with the pump.
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mas985 said:
The app is either flow rate or % rpm. I calculated rpm to be 87% to be at 3k which I use as the reference. Not sure what the flow is at that rpm. If I turn off the booste, the air in the pot comes back, even at 3K rpm.
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Are you running the pump in VS (RPM) or VF (GPM) mode?

When in VS mode, the addition of the booster would increase the flow rate slightly which might improve the expelling of air in the pump basket as well as increasing the suction in the pump basket thereby helping to seal the pump lid.

The bottom line is if there is air in the pump basket and running at high speed does not clear the air, there is an air leak somewhere and most likely it is the pump lid.

Have you done this yet?
mas985 said:
I would check the pump lid and drain plug gaskets for cracks and lube them well with pool lube. If that does not work, then move on to any o-rings you might have on the suction side of the pump.
Click to expand...
 
mas985 said:
Are you running the pump in VS (RPM) or VF (GPM) mode?

When in VS mode, the addition of the booster would increase the flow rate slightly which might improve the expelling of air in the pump basket as well as increasing the suction in the pump basket thereby helping to seal the pump lid.

The bottom line is if there is air in the pump basket and running at high speed does not clear the air, there is an air leak somewhere and most likely it is the pump lid.

Have you done this yet?
Click to expand...
I run in GPM mode most of the time. I use RPM mode on the quick clean option set to calculated 3K rpm and I use that value to check DE filter pressure. With clean filter and 3K I have 20 psi at the filter. The air is gone when I have to booster on but returns in a couple of hours after I turn off the booster even running at 3K rpm.
The pump is only a few weeks old. I did remove and lube up the two drain plugs on the pump as well and took out the lid o-ring and cleaned/lubed it. The lid is different in that the clear part appears to be an insert inside of the ring that tightens the lid. It has an o-ring in it too, but I can't see how it would come out.
Is there any way that too large of a pump could be the issue? I was a 1.5 single speed Challenger and replaced with 3hp VSF. Pipe is 1.5" for the most part.
 
Woody007 said:
I run in GPM mode most of the time. I use RPM mode on the quick clean option set to calculated 3K rpm and I use that value to check DE filter pressure. With clean filter and 3K I have 20 psi at the filter. The air is gone when I have to booster on but returns in a couple of hours after I turn off the booster even running at 3K rpm.
The pump is only a few weeks old. I did remove and lube up the two drain plugs on the pump as well and took out the lid o-ring and cleaned/lubed it. The lid is different in that the clear part appears to be an insert inside of the ring that tightens the lid. It has an o-ring in it too, but I can't see how it would come out.
Is there any way that too large of a pump could be the issue? I was a 1.5 single speed Challenger and replaced with 3hp VSF. Pipe is 1.5" for the most part.
Click to expand...
Are you able to continually expel air from the filter at the air relief valve? Do it once, come back a few minutes later and try again. Is it a lot or just a quick spurt? Seeing no air in the pot used to be the standard to judge by. Now, with VSPs, it isn't. You get used to it.
My VSP will, on a rare occasion, have no air visible in the pot, usually right after a filter cleaning. Most of the time it does show what appears to be some. Yet, I am seldom able to get more than a quick spray of air from the filter, even at low speeds.
I know my pool equipment, like most eventually, has a small leak somewhere that allows the filter to drain each day after the pump shuts off. There is never water anywhere. Some leaks will allow air in but are small enough to not allow water out.
 
PoolStored said:
Use a dental pick, tooth pick, small fork, don't damage it, but get it out and lube it. Clean both mating surfaces.

Please give us exact make and model of the pump.

Pictures of your pad would help...
Click to expand...
This is the pump IntelliFlo3® Variable Speed & Flow Pool Pump
The O-Ring in the lid is trapped between the clear cover and the threaded lid. There is the normal o-ring in the basket top that I can remove like normal, just not the other one.
 
1poolman1 said:
Are you able to continually expel air from the filter at the air relief valve? Do it once, come back a few minutes later and try again. Is it a lot or just a quick spurt? Seeing no air in the pot used to be the standard to judge by. Now, with VSPs, it isn't. You get used to it. Little to no air comes out of the relief valve.
My VSP will, on a rare occasion, have no air visible in the pot, usually right after a filter cleaning. Most of the time it does show what appears to be some. Yet, I am seldom able to get more than a quick spray of air from the filter, even at low speeds. I'd estimate that there is an inch if not two of air. It's realling rolling too. I can't see if it's coming in the inlet or where. I tried at night with a flashlight but can't see past the surface.
I know my pool equipment, like most eventually, has a small leak somewhere that allows the filter to drain each day after the pump shuts off. There is never water anywhere. Some leaks will allow air in but are small enough to not allow water out.

Honestly I wouldn't mind the air, but if I run the pump at low flow (like ~20-25gpm) it will eventually start pushing air out the returns. Maybe my expectations aren't correct, but I thought the point was to run it slow for most of the time and speed it up for a short period of time. For now I'm running 43gpm for 12hrs and 30 GPM overnight. That seems to be enough to keep the air pocket from getting too large.
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Woody007 said:
The O-Ring in the lid is trapped between the clear cover and the threaded lid. There is the normal o-ring in the basket top that I can remove like normal, just not the other one.
Click to expand...

Post pictures please of the pump basket without lid, and the underside of the lid. I want to see all the o-rings/sealing surfaces.
 
I'm going through the same issue - turns out mine is two defective valves. One massive, so easy to find. But the other was a VERY tiny hairline crack, but no water leak. Under full speed all is fine, but under reduced, the pot and filter slowly fill with air. With system off, filter drains itself. Waiting on the brown truck for the parts now...
 
PoolStored said:
Post pictures please of the pump basket without lid, and the underside of the lid. I want to see all the o-rings/sealing surfaces.
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Hears some pictures. I think the ring in the lid is a flat washer. The lid seams to seal tightly.
I tried to get some pictures of the air bubbles but too much reflection.
 

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If the air is continuous you have a suction leak. It is now time to try everything in front of the pump along with the lid O ring and the drain plugs on the pump. Those plugs are the cause of many suction leaks and often just overlooked. They're not supposed to, but on occasion they will vibrate loose enough to suck air but not leak water. Give them a tiny twist closed to be sure.
Make sure the union in front of the pump is tight, but don't use a tool as you would likely break the nut. You might want to remove the union far enough to coat the O ring with some pool lube.
Are there any valves in front of the pump? They can be a source of air as well.
 

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