Underground Leak?

[Cherry Tree Pool]

It started out as just a lot of air bubbles from the return jets. But after being away for a few days I returned to a very green pool. The filter was not moving much water, many air bubbles and the pump basket was probably half full. I couldn't locate the air leak and get the water moving so broke down and called a pool repair company. They pressure tested the line and said the pressure didn't hold (went to zero). They recommend digging up the old line and putting in a new line. They cut the suction line at the pump and placed a temporary line directly into the pool bypassing the skimmer.
My question is: The skimmer has been isolated from the pump for about 5 days, but there is still water in the skimmer and the line. If there was an underground leak wouldn't the skimmer and line lose water? Or wouldn't I be losing water from the pool? Is there another test that can be done to confirm the line has to be replaced?
FYI, I do not have a main drain and the pool only has one skimmer. The second one was sealed off when a different pool service said it was unusable.
Thanks for any advice.

 

[ajw22]

Did you test if you lost water from the pool with the pump off?

The problem in the skimmer suction line probably only loses water and shows itself when there is suction and water flow though it.

 

[Cherry Tree Pool]

Thanks Allen. Right now I am slamming so I haven't turned off the filter. But since there is no water going through that line would turning off the filter test for water loss?
I guess my interpretation from the pool guy was that the line was broken so I assumed it would leak. If I understand you, the line will only leak while suctioning water through it.

 

[mknauss]

A suction line leak will pull air in when the pump is running, but leak water out when the pump is not. As you now have that line out of the pump system, unless the pool service plugged the line at the skimmer, you should be having some amount of water leaking from the pool. May not be great amounts.

 

[ajw22]

Thanks Allen. Right now I am slamming so I haven't turned off the filter. But since there is no water going through that line would turning off the filter test for water loss?

You would have needed to test that before you cut the suction line.

I guess my interpretation from the pool guy was that the line was broken so I assumed it would leak. If I understand you, the line will only leak while suctioning water through it.

Pipe doesn’t need to be broken. More likely a leak in a joint.

Problem was air was being sucked in as water was flowing. It does not mean water will leak out when no suction or water flow.

 

[Cherry Tree Pool]

Thanks for your replies. The line was not capped at the pump. They cut it to do the pressure test. I will watch for water loss. Would a plumber with a camera be able to locate the leak?

 

[ajw22]

Thanks for your replies. The line was not capped at the pump. They cut it to do the pressure test. I will watch for water loss. Would a plumber with a camera be able to locate the leak?

Not if it sucks in air from a joint. It will look fine.

PVC pipes are glued together. The joints are often the weak spots to suck in air.

 

[Cherry Tree Pool]

Thanks for the clarification. That makes sense.

 

[1Sammy]

I bet ya they left the test plug in the skimmer so there would be no water lost. If not and there is no lost then i would be concerned. Once the ground in the area of the leak is saturated heavy with water the lost of water going out will be very low but if it was still hooked into the system as it was before they cut it then in short time the suction would take all the water from the ground and then the air would start again. Pressure test is the right and fastest way to do it IF they did it right at the line where it comes into the pump as they will cancel out gaskets / plugs / seals.