Suction leak

Leaks in the pool, plumbing, filtration system, skimmer, ...
Finding & repairing swimming pool leaks.
cstanton
I'm new here
I'm new here
Posts: 3
Joined: Tue 24 Aug, 2010 08:33
My Pool: 20 X 40 in ground gunite

Suction leak

Postby cstanton » Tue 24 Aug, 2010 08:40

I have air in the return jets of my pool. So far I have done the following.

1. Replaced the gasket and sealed the input line to the pump.
2. Replaced the pump lid gasket.
3. Replaced all of the seals in the two valves that control water flow from the skimmers and the drain.
4. Replaced and sealed the two drain plugs on the pump.

This phenomenon just appeared a few weeks ago. From what I have read; air in the return jets is an indication of a suction side leak which would include anything from the input side of the pump out to the pool as well as the pump drain plugs and the pump lid gasket. The water level is stable so I can safely say I do not have a water leak.

I tested setting the suction side valves as described below in an attempt to isolate the cause.

1. Drain only
2. Shallow Skimmer only
3. Deep Skimmer only

Neither of these improved or worsened the amount of bubbles I was seeing in the return jets.

I have read that another possible cause is the pump seal. Is this true or am I missing something else?


User avatar
mas985
Swimming Pool Pro
Swimming Pool Pro
Posts: 199
Joined: Tue 08 Sep, 2009 10:40
Location: Pleasanton, CA, USA

Suction leak

Postby mas985 » Tue 24 Aug, 2010 09:51

Pump shaft seals are on the pressure side of the pump so you would see water dripping out of the pump rather than air getting sucked in. A few things that can cause air in the returns.

Air in the pump basket would indicate a suction side leak but it sounds like you checked everything. But if you do have air in the pump basket, you probably still have the air leak.

No air in the pump basket and diminishing air in the returns over time could mean a spider gasket leak that allows air into the filter when the pump is off. Over time the air gets purged out and should diminish.

None of the above but you have a salt water chlorinator can also mean small hydrogen bubbles in the return.
Mark
Hydraulics 101; Pump and Pool Spreadsheets; Pump Ed 101
18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, Solar Panels, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater
duraleigh
Swimming Pool Wizard
Swimming Pool Wizard
Posts: 81
Joined: Sat 07 Aug, 2010 23:26
My Pool: 24X52 DIY Concrete and liner
Location: Raleigh NC

Suction leak

Postby duraleigh » Tue 24 Aug, 2010 10:18

The most common cause is improper seating of the pump strainer basket lid....you seem to have addressed that.

Not a common source but a possibility is the drain plugs at the bottom of the pump strainer basket could be slightly loose and air would be sucked in there....are they tight?

Can you see air bubbles in the pump strainer basket?

Do the bubbles decrease in time or do they stay the same as long as the pump is running?
24x52 DIY concrete block and liner
1.5HP pump 925lb sand filter
http://www.tftestkits.net
Guest

Suction leak

Postby Guest » Tue 24 Aug, 2010 12:51

I can see bubbles in the strainer basket. They appear to come in from the suction line; however it is hard to tell for sure.

What is a spider gasket leak?

I keep asking myself "What would cause this to happen overnight?"
ChuckGeo
Swimming Pool Pro
Swimming Pool Pro
Posts: 103
Joined: Fri 16 Jan, 2009 16:31
Location: Atlanta, GA.

Suction leak

Postby ChuckGeo » Tue 24 Aug, 2010 15:05

If the air is present in the same quantity no matter how you have the suction valves set, skimmer off or main drain off, it sounds like something in the suction manifold or suction side of the pump - lid gasket or drain plugs, or a crack in the pump housing. When you turn off the pump does water squirt out anywhere? If water squirts out somewhere at the suction side, that could be the location of the air leak. You might also direct a stream of water, garden hose, over the suction side, with the pump on, and see if the air bubbles in the pump stop when the water covers a certain area.
Chuck
Owner, Superior Pool Services
25 years leak detection experience
duraleigh
Swimming Pool Wizard
Swimming Pool Wizard
Posts: 81
Joined: Sat 07 Aug, 2010 23:26
My Pool: 24X52 DIY Concrete and liner
Location: Raleigh NC

Suction leak

Postby duraleigh » Tue 24 Aug, 2010 15:22

What is a spider gasket leak?.....not applicable since you can see bubbles in the strainer basket
I keep asking myself "What would cause this to happen overnight?"....don't know.


Did you check the drain plugs? If not there. then you must recheck every possible source for air to enter the line between the strainer basket and the skimmer.

Can you confirm the gasket is seated correctly on the strainer basket lid?
24x52 DIY concrete block and liner
1.5HP pump 925lb sand filter
http://www.tftestkits.net
floridapooltech
Swimming Pool Superstar
Swimming Pool Superstar
Posts: 307
Joined: Wed 17 Feb, 2010 22:47
My Pool: License # CPO34-283076
Location: Tampa Bay, FL
Contact:

Suction leak

Postby floridapooltech » Tue 24 Aug, 2010 18:35

It is possible the problem is underground with the suction side pipework. You may have a loose coupler or elbow fitting, or a crack in a pipe.
cstanton
I'm new here
I'm new here
Posts: 3
Joined: Tue 24 Aug, 2010 08:33
My Pool: 20 X 40 in ground gunite

Suction leak

Postby cstanton » Wed 25 Aug, 2010 05:57

One thing I should mention is the amount of bubbles I see in the strainer basket is small. I can almost count them; however on the jet side I see a cyclical blast of bubbles coming out.

I am wondering if the pump is somehow damaged.

When I closed the pool last fall; I overpressurised the pump enough to crack the lid.

I replaced the pump lid and gasket in the spring and had no issues till this occured a few weeks ago.
floridapooltech
Swimming Pool Superstar
Swimming Pool Superstar
Posts: 307
Joined: Wed 17 Feb, 2010 22:47
My Pool: License # CPO34-283076
Location: Tampa Bay, FL
Contact:

Suction leak

Postby floridapooltech » Wed 25 Aug, 2010 10:50

cstanton wrote:One thing I should mention is the amount of bubbles I see in the strainer basket is small. I can almost count them; however on the jet side I see a cyclical blast of bubbles coming out.

I am wondering if the pump is somehow damaged.

When I closed the pool last fall; I overpressurised the pump enough to crack the lid.

I replaced the pump lid and gasket in the spring and had no issues till this occured a few weeks ago.



How much pressure are we talking, enough to crack a pipe or loosen a fitting?
cstanton
I'm new here
I'm new here
Posts: 3
Joined: Tue 24 Aug, 2010 08:33
My Pool: 20 X 40 in ground gunite

Suction leak

Postby cstanton » Wed 25 Aug, 2010 11:29

Enough to crack the pump lid and send it flying into the air. The skimmers and drains were shut off at the valve; so nothing should have gotten by them.

I had the multiport valve in a position that bassically only allowed me to pressurize the pump.
User avatar
mas985
Swimming Pool Pro
Swimming Pool Pro
Posts: 199
Joined: Tue 08 Sep, 2009 10:40
Location: Pleasanton, CA, USA

Suction leak

Postby mas985 » Wed 25 Aug, 2010 13:44

That sounds like your filter is filling with air which is creating the very high back pressure. Air is compressible but water is not so if there is a lot of air in the filter and the pressure is fairly high, it will create a lot of back force when the pump is shut off and can easily blow a lid off a pump.

Normally, filters will self purge the air via vent pipe in the filter so you might what to check that. Here and here are videos that shows what can happen when there is too much air in the filter.

The next step is to figure out where the air is comming from. As I posted before it is usually an air leak from the suction side of the pump which will draw in air when the pump is running. The small air bubbles could be an indication of this although the filter should be able to purge that amount of air if the vent tube is clear.

However, another cause is a leak in the backwash valve gasket so the filter will suck in air when the pump is off. It may not leak water when it is on either so it isn't always easy to tell. However, when the pump is shut off, you can hear the water draining and air bubbling through the filter so that is usually a good sign that the filter may have an air only leak.
Mark
Hydraulics 101; Pump and Pool Spreadsheets; Pump Ed 101
18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, Solar Panels, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater
ChuckGeo
Swimming Pool Pro
Swimming Pool Pro
Posts: 103
Joined: Fri 16 Jan, 2009 16:31
Location: Atlanta, GA.

Suction leak

Postby ChuckGeo » Wed 25 Aug, 2010 14:34

If the you are only seeing a small amount of bubbles in the pump and getting bubbles out of the returns sporadically, it may be that when the bubbles go through the pump and into the filter they build up in the filter, then escape through the auto air relief in the filter and out the returns. If you are getting air in the pump you need to concentrate on the suction side of the system, downstream of the pump is under pressure and won't let air in the filter.
Does your vacuum work OK? Does the air in the pump increase when you hook up the vacuum? You may not have a big enough problem to worry about, or you may want to call in a pro for help.
Chuck

Owner, Superior Pool Services

25 years leak detection experience
rww

Suction leak

Postby rww » Wed 25 Aug, 2010 19:07

I had a similar situation. Turned out to be aleak in an o-ring in a Pentair valve just before the pump.
maybe

Suction leak

Postby maybe » Fri 27 Aug, 2010 09:22

do you have a automatic suction pool cleaner? if so unplug it and see if the air bubbles go away, if they do check the hoses.

when theres an air leak it's from skimmer to pump thats it anything beyond pump would leak water not suck air.
bsw

Suction leak

Postby bsw » Sun 03 Nov, 2013 21:08

This is pretty old but...An Ozone Generator will create larger bubbles in the gasket and create an abundant amount of small bubbles usually through one and not all of the returns. At least that is how mine operates.

Return to “Swimming Pool Leaks”

Who is online at the Pool Help Forum

Users browsing this forum: No registered users and 12 guests