Skimmer lid flying off and loud "whooshing" sound heard when pump turned off

channing321

Member
May 23, 2017
24
Mesa, AZ
This issue has been driving me nuts for some time now.

When I turn the my pump off I hear a loud whooshing sound and water backs up through the plumbing and comes out of the skimmer, sometimes with so much force it blows the lid off. It also will push the weir flap up into a stuck position so the next time the pump turns on it has an extra hard time priming.

I've read a lot about it being a suction air leak. I added pool water and it persisted. I changed the pump drain plug and gasket, the housing gasket, the diffuser gasket, the jandy valve gasket just before the pump, and the pump basket lid gasket. I've tried soap suds to see if I have an air leak in one of the glued fittings but no suds get sucked in anywhere.

When I open the sand filter air release, initially lots of air is pushed out and then water comes out but air still is coming out with the water in small spurts. It is never a nice steady stream of water coming out of the release.

The ONLY thing I've done that has temporarily fixed it, is to backwash the pool. I backwashed 2 nights ago and the sweet sound of silence followed when I ran the pump and shut it off. The next day however I had the problem back again. I have added DE to my filter in the past. Is this possible a part of the problem?

Tonight, after adding more water than I like to see if that would help, I backwashed for about 2 minutes to bring the water level down a little and the problem went away. When I open the air release on the sand filter it's a nice steady stream, and when I turned the pump off, it's silent and maintains prime. This was about 10 minutes ago.

I'm letting the pump run tonight and then I'll check it again in the morning after it's had some time to be off, but this is driving me crazy! Any ideas, tips, tricks are more than welcome. Thanks in advance!
 

JamesW

TFP Expert
Mar 2, 2011
22,127
It’s air getting in the filter. The air is compressed and then it decompresses when the pump is off. You can solve the symptom by putting a check valve between the pump and filter. To solve the actual problem, you have to fix the suction side air leak.

The pump is probably oversized for the filter, which creates excessive pressure, which creates more compressed air and more backflow when the pump is off.

If you can push water into the pump with a garden hose, that might reveal the leak. Watch the skimmer weir to see if it’s getting stuck and causing air to get sucked in at the skimmer.
 

channing321

Member
May 23, 2017
24
Mesa, AZ
Thank you for the quick reply.

I've owned this pool for 4 years almost and only in the last year has this problem cropped up, so I'm unsure if the pump is oversized. I have a Hayward SP3010EECP Super II pump.

Where would I push water through the pump with a garden hose?

I watched the skimmer and the weir for 20 minutes while adding water tonight and saw little whirpools from time to time, but the flap never got stuck. It only gets stuck when the pump turns off and blasts water in reverse, forcing the flap into a closed position.
 

ajw22

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Jul 21, 2013
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Northern NJ
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I've owned this pool for 4 years almost and only in the last year has this problem cropped up, so I'm unsure if the pump is oversized. I have a Hayward SP3010EECP Super II pump.

And it is likely for 4 years your pump has been pressurizing your filter. Your pool plumbing would hold the pressure until you developed an air leak.

Pull a straw out of a glass of water with your finger over it and the water stays inside the straw. This is a pool system without an air leak. Remove your finger and the water falls out. This is your pool with the air leak. It does not take much of an air leak in a valve seal or pipe connection to no longer hold pressurization.
 

duraleigh

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As JamesW said, you have a suction side air leak. There is an article in pool school that may help you find it.

Once you find and fix that leak, (it is virtually NEVER underground) the problem will disappear.
 

Jimrahbe

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321,

The air problem will only happen if your weir door gets stick in the up position.. I suggest that as a test, you stick a brick on the weir door so that it is held in the down position. See if your problem goes away.. Your skimmer will not skim as well, but if the air problem goes away, you will know the weir door is the problem. It is an easy test and can't hurt anything.

If the problem still exists, then you will know that the weir door is not the problem.

*** Edit.. Just to be clear.. I am not saying that you don't have a suction side air leak.. I'm just saying that a weir stuck up will cause the problem you have and that you should eliminate the weir door first, as it is so easy to do..

Thanks,

Jim R.
 
Last edited:

JamesW

TFP Expert
Mar 2, 2011
22,127
I have a Hayward SP3010EECP Super II pump.
The pump is oversized for a single skimmer and the filter. You can use it like it is or maybe replace the impeller with a smaller impeller.

You can rig up an adapter so you can use a garden hose to push water to the pump from the skimmer hole.
 

channing321

Member
May 23, 2017
24
Mesa, AZ
And it is likely for 4 years your pump has been pressurizing your filter. Your pool plumbing would hold the pressure until you developed an air leak.

Pull a straw out of a glass of water with your finger over it and the water stays inside the straw. This is a pool system without an air leak. Remove your finger and the water falls out. This is your pool with the air leak. It does not take much of an air leak in a valve seal or pipe connection to no longer hold pressurization.

I want to make sure I have this correct. The pump being oversized over pressurizes the system, more likely causing an air leak?
 

channing321

Member
May 23, 2017
24
Mesa, AZ
The pump is oversized for a single skimmer and the filter. You can use it like it is or maybe replace the impeller with a smaller impeller.

You can rig up an adapter so you can use a garden hose to push water to the pump from the skimmer hole.

I'll look into replacing the impeller and/or the pump. Would the oversized pump increase the chance of an air leak?

I'm sorry for the newbie question but want to make sure I know what I'm looking for. I'll turn a hose on and stick it in the skimmer hole with the pump off. Will water leak from the location of the air leak?
 

channing321

Member
May 23, 2017
24
Mesa, AZ
Why does the air leak temporarily go away when I backwash? Is it because backwashing finally removes all the air out of the filter and after the pump runs for a few hours it has had time to suck enough air back in to not hold prime?

And my wife suggested it was our pool cleaner. She said the basket looks like it's always floating with more air in it than it used to have. I just disconnected the pool cleaner completely. Then I backwashed and relieved the air from the filter so it will hold prime. I'm going to run the filter for a few hours and then turn it off and see what happens.
 

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JamesW

TFP Expert
Mar 2, 2011
22,127
A dirty filter creates more resistance, which causes the air to compress more.

The oversized pump creates more pressure, which causes the air to compress more.

To push water from the skimmer hole, get a threaded adaptor from the hardware store that will adapt from the skimmer hole to the garden hose.
 

JamesW

TFP Expert
Mar 2, 2011
22,127
If you have a suction cleaner connected to the skimmer, that can be the source of the air leak.
 

channing321

Member
May 23, 2017
24
Mesa, AZ
A dirty filter creates more resistance, which causes the air to compress more.

The oversized pump creates more pressure, which causes the air to compress more.

To push water from the skimmer hole, get a threaded adaptor from the hardware store that will adapt from the skimmer hole to the garden hose.

I see. Very helpful information. I'll try the garden hose today. And I would see water coming out of the location of the air leak doing this method?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
22,309
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
I want to make sure I have this correct. The pump being oversized over pressurizes the system, more likely causing an air leak?

No, you have two independent problems.

The pump and filter pressurization has likely been going on for years and is relatively benign. You would not see it as long as your plumbing was tight with no air leaks and stays pressurized.

Within the last year you developed an air leak. That is like taking your finger off the straw. Now you see the other problem also. If you did not have the filter pressurization teh air leak would have shown itself in other ways.

If you only fix the pump by changing the impeller you will have treated the symptoms and not the disease. The air leak will cause other problems if left there.
 

duraleigh

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This thread is starting to confuse me! Channing321, You have a suction side air leak. Did you read the article in Pool School?

Find and fix that leak and you will fix the problem.

Don't change anything else.
 

channing321

Member
May 23, 2017
24
Mesa, AZ
From pool school:

1. The most common source is the pump basket lid. It must have an airtight seal. Replacing the O-ring often helps. Proper cleaning and lubrication of the O-ring with a silicone based lubricant (Magic Lube is one brand) may be necessary….do not use WD-40 or petroleum jelly.

I replaced and lubricated the pump basket o-ring. Seal is tight, no reaction from soap suds getting sucked in.

2. Most all pumps have two drain plugs. One is near the bottom of the basket and the other further back on the motor side of the pump. Only the basket drain can introduce air into the pump. Remove the plug and inspect the O-ring. Replace if split or deformed, lube the O-ring and reinstall the plug snugly.

I replaced the basket drain plug and o-ring.

3. Poorly made or broken, cracked PVC joints. If it looks sloppily made or crooked, it should be VERY suspect. Sometimes you can identify them by using the same running water technique as the one for the lid above. The fix is to cut out and remake that joint.

The only PVC joints are immediately before the pump. They look solid and I get no reaction or sucking in with soap suds.

4. All valves. They can be cracked or perhaps need new seals. Identify by listening (very close) or using the running water test again.

The jandy valve right before the pump had it's o-ring replaced 3-6 months ago. I had this problem and thought I completely solved it when I replaced a very sad looking o-ring in the jandy valve. I reinspected the jandy valve and o-ring. All looks good.

5. The pool water level. Pump running, visually inspect the skimmer to make sure absolutely no air is “whirlpooled” down into the skimmer. That’s a fairly common cause and an easy fix….add more water to the pool and make sure that the weir (flapper) door operates correctly.

I increased the water level even though I have not had problems in the past at the same level. I have an autofill that maintains the level.

6. If your pump or plumbing “spits” a little water from somewhere when the pump shuts off, that often indicates the location of an air leak.

I watch each section when I turn off the pump and do not notice any water "spitting" from anywhere.




I disconnected the pool cleaner and completely removed it from the water to eliminate the potential for it to be a hose with a small hole in it. I ran the pump for 5 hours and then turned it off for 3 hours. When I went out to check on it, I turned it on and it worked immediately but I could tell that there was a small amount of air in the pump basket. So, I clearly still have the air leak, I'm just getting stumped on where it might be.

I tried the garden hose in the skimmer but I couldn't find a nice adapter at Lowe's to screw my hose into and then into my skimmer to create a good seal so it was probably kind of pointless. Does anyone have a link to an adapter that screws into the skimmer and then a garden hose?

Does anyone have any ideas that are not mentioned in the pool school article or tips or tricks to try and find this leak? I know I have one I just can't seem to find it!
 

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