Pool Suction Leak

Leaks in the pool, plumbing, filtration system, skimmer, ...
Finding & repairing swimming pool leaks.
jim1504
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Pool Suction Leak

Postby jim1504 » Wed 18 Mar, 2009 11:47

I have a 15k gal gunnite pool/spa. I'm having a problem with excess air in the pump strainer basket which has been causing substantially reduced suction to operate my Kreepy. After initially opening the filter cartridge canister, the pump will expel about 95% of the air in the pump basket. After 10 mins, the pump basket has about 50% air to water.

I checked all above ground lines, pool filter & pump with soapy water (turning the pump motor on and off & watching). No signs of even a slight leak. I next blocked each line at the pool individually (except the main drain) & found no change in the amount of air in the system.

I think that my next test is to have the lines pressure tested. My question is whether 50% of air in the basket could be an underground leak? It seems to me that there would not be that amount of air available underground. Of course 90% of the underground pipe is covered by concrete patio so I'm not sure what could be happening there. Another question is whether this could be a pressure leak since it is taking in so much air? Thanks for any help!
Jim


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Larry
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Pool Suction Leak

Postby Larry » Wed 18 Mar, 2009 13:25

Hi Jim and welcome to the forums

You wrote:I next blocked each line at the pool individually (except the main drain) & found no change in the amount of air in the system.


This would imply that the leak is independent of the suction pressure, although it is somewhere on the suction side.

Some of the more obvious places the pump sucks air from are the pump basket cover, valves, threaded connections and pump adaptors. If the Kreepy is connected, the pump can even draw air in through abrasions on the vacuum hose.

To determine which suction line is allowing air into the system, first purge the air and then leave only one suction line open at a time. Then you can determine how much air is being taken in and how fast for each suction line.

You wrote:It seems to me that there would not be that amount of air available underground.

It doesn't take much air in the pump to cause the impeller to start cavitating and losing pressure. If there is a pipe leak then the escaping water will erode away the ground thus enabling air to be sucked in more easily.

I hope this has begun to narrow down the possibilities

Larry
jim1504
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Pool Suction Leak

Postby jim1504 » Wed 18 Mar, 2009 16:38

Thanks Larry, that does help. I will try restarting the pump process blocking each individual line. Tonight I will also use a new strainer basket & filter to since my brother has the same filter & same pump. I've been leaving the Kreepy unhooked to leave it out of the equation.

Thinking about it now, what is strange is that the air will purge initially from the system when the filter cover is off no matter where the valves are turned.


Larry wrote:Hi Jim and welcome to the forums

You wrote:I next blocked each line at the pool individually (except the main drain) & found no change in the amount of air in the system.


This would imply that the leak is independent of the suction pressure, although it is somewhere on the suction side.

Some of the more obvious places the pump sucks air from are the pump basket cover, valves, threaded connections and pump adaptors. If the Kreepy is connected, the pump can even draw air in through abrasions on the vacuum hose.

To determine which suction line is allowing air into the system, first purge the air and then leave only one suction line open at a time. Then you can determine how much air is being taken in and how fast for each suction line.

You wrote:It seems to me that there would not be that amount of air available underground.

It doesn't take much air in the pump to cause the impeller to start cavitating and losing pressure. If there is a pipe leak then the escaping water will erode away the ground thus enabling air to be sucked in more easily.

I hope this has begun to narrow down the possibilities

Larry


Well I was hoping for an above ground leak but that would rule it, as being the sole possibilty, out. I always suspected a below ground leak and that may be where it is. I will try what you suggested above to try to narrow it down. Thanks for the help!
Jim
jim1504
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Pool Suction Leak

Postby jim1504 » Thu 19 Mar, 2009 11:23

I re-tested each of the lines seperately (spa, kreepy, skimmer) after first priming the pump. All lines result in the same effect - 50% air in the pump. My plan is to replace the PVC leading from the main vale to the pump. I may just also replace all 3 valves since they are 15 years old & do not appear to be making a complete seal from one line to another. Does anyone suspect it might be a problem with the pump such as a partially defective impeller?
Thanks
Jim
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Pool Suction Leak

Postby greg340 » Thu 19 Mar, 2009 13:21

Check the pump lid gasket. Most people over look it. Make sure its in place ,clean it. Also clean off the lid where the gasket sits. They both build up with dirt and junk. Lightly grease both. I've been on more service calls then i can remember and found the gasket on the ground near the pump and heard "Yeah I saw that I didn't think it was important"...
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Pool Suction Leak

Postby ChuckGeo » Thu 19 Mar, 2009 13:54

Given that you've valve off each suction line individually and get the same reduced water level in the pump, the pump lid is lubed and you see no water coming out of the suction manifold or pump when the pump is turned off - I'd suggest checking the impeller for clog. A clogged impeller can mimic an air leak, i.e. the pump won't fill up with water. You should be able to reach the front of the impeller without disassembling the pump. TURN OFF THE PUMP, remove the basket, and reach into the suction port at the back of the pump pot with a needle nose plier or a hemostat. You may feel the clog as a soft mass, pick it out (it can take several attempts) and try the pump.
Good luck.
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jim1504
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Pool Suction Leak

Postby jim1504 » Fri 20 Mar, 2009 11:29

greg340 wrote:Check the pump lid gasket. Most people over look it. Make sure its in place ,clean it. Also clean off the lid where the gasket sits. They both build up with dirt and junk. Lightly grease both. I've been on more service calls then i can remember and found the gasket on the ground near the pump and heard "Yeah I saw that I didn't think it was important"...


Thanks Greg. Thats what I suspected so I thoroughy cleaned & lubed the strainer basket & also used my brothers lid since he has the same model pump. No change. Thanks for offering the suggestion

ChuckGeo wrote:Given that you've valve off each suction line individually and get the same reduced water level in the pump, the pump lid is lubed and you see no water coming out of the suction manifold or pump when the pump is turned off - I'd suggest checking the impeller for clog. A clogged impeller can mimic an air leak, i.e. the pump won't fill up with water. You should be able to reach the front of the impeller without disassembling the pump. TURN OFF THE PUMP, remove the basket, and reach into the suction port at the back of the pump pot with a needle nose plier or a hemostat. You may feel the clog as a soft mass, pick it out (it can take several attempts) and try the pump.
Good luck.


Hi Chuck
My brother was mentioning a block in the pump but I thought it must be an air leak. After reading your post I drained the pump and reached up in there - nothing. Also looked up there with an inspection mirror and everything was perfectly clear. I turned the pump on/off a few time to try to clear it. This morning I looked in the stariner basket that I removed last night & it had a couple of larger pieces of plastic in it. I decided to prime the pump & test it. Pump worked perfectly & was much quieter! I left for work 1/2 hour later & everything was still working great. Hopefully all is well when I get home but I think that cleared it. I think I should take off the pump & see if anything else is to the rear of the impeller. What do you think? Thanks for nailing the problem!
Jim
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Pool Suction Leak

Postby forboon » Thu 04 Jun, 2009 17:42

I was looking around this site for numerous problems I have had and figured i'd at least give back some that I have learned. I had little pressure coming from my returns and small bubbles too. was worried there was a suction side like. eventually my creepy crawler wouldn't run, my pump would completely lose its prime and there was no water flow. in desperation I took the pump apart (was quite easy) and realized 2 of the four impeller sections where clogged. with a wire and about half an hour I unclogged it and the pump runs twice as good as it used and there are no bubbles. there's no way i could check the impeller or clear the debris without opening it, and taking out a few screws TO THE POINT WHERE I COULD SEE THE IMPELLER HOLES. any handy person could do it, i think
justin

Pool Suction Leak

Postby justin » Mon 02 Aug, 2010 09:33

My pool is losing approximately 1 inch a day and the main drain line is pulling air. Can this be fixed with the "pipe down under", where you pull a pipe through the drain line? Thanks.
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Pool Suction Leak

Postby floridapooltech » Mon 02 Aug, 2010 11:04

justin wrote:My pool is losing approximately 1 inch a day and the main drain line is pulling air. Can this be fixed with the "pipe down under", where you pull a pipe through the drain line? Thanks.


this issue can be fixed. The best thing to do is contact a leak detection company in your local area. They will run a pressure leak test on your entire shell to see where the leaks are coming from. They typically will go in with full scuba equipment, so if the problem is with your main drain, this should not be an issue!
Florida Pool Tech is a Florida certified service company headquartered in Tampa, Florida employing the best technicians and installers in the industry! Vist us at http://www.floridapooltech.com

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