Leak diagnosis

chrisexv6

Well-known member
Feb 8, 2008
340
Milford, CT
My pool lost 1/4" of water in 24 hours, and since Ive suspected it was leaking, this is pretty good confirmation Im correct!

I have 2 suction side inlets (one skimmer, one main drain) and 2 returns. I sealed off the returns and the skimmer, but obviously its almost impossible to seal off the main drain. With 3 of the 4 ports sealed off, the pool lost 1/4" of water in 24 hours.

So its either the liner or the main drain. I do NOT get any air in the suction or return sides with the filter running, but I suppose there is a small chance the water can be trickling out of the main drain pipe with the system off, but the leak might seal itself with the system on.

Does anyone have any suggestions on narrowing down liner vs main drain? The only way I can think of to seal the main drain is to send in a diver, but at that point I can have the diver search the liner for a leak too.

Thanks in advance.

-Chris
 

guamguy

LifeTime Supporter
Feb 26, 2010
388
Guam, USA
I would try the bucket test twice, once with the pump running, and again with it off. This would narrow down if it's the liner or main drain. Do you have valves to adjust the suction between main drain or skimmer? This would let you put full suction on the main drain and see if the leak stops when the pump is running.
 

chrisexv6

Well-known member
Feb 8, 2008
340
Milford, CT
OK, I ran the experiment for 4 days total. 2 days with the filter off and the 2 returns and skimmer plugged. The other 2 days with everything running and unplugged.

During the days with the filter off, I lost more water in the pool than the bucket.

During the days with the filter ON I lost the same amount (or very close to) of water in the pool as I did the bucket

So, does that mean the leak is the main drain? Since I couldnt seal it for the "filter off" days. I figured if the liner was leaking it would leak regardless of filter on or filter off.

Strange thing is that I dont get any air or water loss with the filter running, so maybe its sealing itself back up once under suction from the filter ?
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
11,077
Houston, Texas
If you have a waste line, make sure it is not leaking when the pump is running. 1/4" loss would probably be a slow trickle.
 

Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2009
23,045
SouthWest Alabama
If that's true then what you have is a suction side leak. It's may not leak much air in when running but it apparently is leaking water out when it's not.
 

chrisexv6

Well-known member
Feb 8, 2008
340
Milford, CT
Its actually past time to close the pool. Since it looks like the main drain is leaking, Im guessing I need to pay a diver to get down there and plug it up? Otherwise I cant close the pool without losing all of the water over the winter (thereby collapsing the pool, which at this point isnt a bad idea to me!! the wife and kids dont agree though)
 

waste

TFP Expert
LifeTime Supporter
Mar 29, 2007
4,160
Coastalish 'down easter'
Hey, I've followed this thread and you've got the worst that I suspected :evil:

As has been said, it certainly looks like the MD line has a leak that is ameliorated when the pump is running, the suction on the line keeps the water from leaving the pool.

I fear you'll need to plug the line for the winter to prevent major water loss :(

However, with the plug in place you can pressure test the line to get an idea, not only of how large the leak is, but possibly the location :)

It SUCKS to close a pool knowing there's a problem, but we can deal with it next spring. The important thing is to keep the pool viable until we can properly address the problem.
 

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