Air leak in return lines


New member
Jun 28, 2010
We purchased our home in the summer of 2008. We have an IG pool built about 20 yrs ago. Upon opening pool there was a massive rip in one corner of the vinyl liner. We finally had money this year to fix the liner and start pool up. I did partially winterize the pool each year- air/water blown out of lines and such. Pool specs are:

pool size: 27K gallons, 20x40 (custom L style)
filter: DE
Vinyl, IG
New Emerson 1 hp pump (no idea on flow rate)

The issue we have is that 1) main drain seems to have been cut off at some point (not sure by whom or why). Previous owners never mentioned this as one of the maintenance tasks performed by them. 2) Right skimmer line was repaired and re-piped with spa hose. The hose is not level with skimmer (goes uphill) and was never buried. It is riddled with holes as the bugs really like to eat this I'm told. 3) We closed off the Right skimmer and we are just using our left skimmer, as we were seeing air in the return. Problem is that the air continues. The plumbing for the left skimmer is definitely well underground.

I have tried pouring water over all the suction side joints to see if I see air bubbles. I don't see a difference. I have bled the air from the filter but this only works long enough for the air to fill up again. I tried the red dye test near the skimmer areas and did not see anything pulling. I need to do a definitive evaporation test but am pretty sure we are not losing water. It's been scorching here so I have dropped about 1.5 inches over the past month.

My pool contractor is too busy right now to help with leak detection. He feels the issue is in the underground plumbing. Do you suggest I hire a professional leak detection company before we spend a ton of money on all kinds of plumbing repairs?

Thank you,

Bama Rambler

Mod Squad
TFP Expert
Bronze Supporter
LifeTime Supporter
Jun 22, 2009
SouthWest Alabama
Welcome to TFP. :wave:

Try running water over the pump strainer housing while the pump is running and see if the air subsides. If it does try lubing the o-ring seal to see if that helps. I'd do that before I called a leak detection service.

If that's not it, post some pics of the pool and equipment and we may be able to give you a better idea of where to start looking.

Melt In The Sun

TFP Expert
LifeTime Supporter
Oct 29, 2009
Tucson, AZ
lilith, welcome to TFP!
Before calling a leak service, I would do a bucket test. If you've lost only 1.5" in a month, it doesn't sound like a leak. I assume you have air in the pump basket. Since it's a brand new pump, I wouldn't expect the strainer basket lid to be pulling air, but that's easy to check. Take off the lid, check to make sure the gasket is seated correctly and nicely lubed up.

As for pouring water on the joints, make sure you leave the hose in each spot for 30 seconds or so, and cup your hand around the pipe so that the bottom side of the joint is sitting in water. If you find the leak, the pump basket won't empty of air immediately; it can take a minute or so. I would suspect the threaded connection on the inlet side of the pump, given that it was just replaced, but it could be anywhere including underground.

Posting details of your pool (with pictures) will help.


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
One thing to consider is that your setup simply may not be able to provide enough water to the pump to keep up. Your system was installed with three pipes providing water to the pump, and you are down to one remaining. It may very well be that your pump is emptying the basket faster than the single skimmer can provide water to refill it.