Trying to Pinpoint Leak

[poolman10]

A leak puzzler for those who like to figure this stuff out:

I have a vinyl inground pool -- one skimmer and one return. There is a main drain, but it is not functional and is completely plugged.

Over the past few weeks, I've noticed that the pool has not been holding its normal level. It's been very hot here with little rain, so attributed the problem to evaporation.

I started adding water (from well) and then we just had a lot of rain a few days ago, but the water level dropped to about 2 inches above the bottom of the skimmer inlet, and then of course it just starts sucking air. At that point, I throw the vaccuum in the pool and circulate the water that way. The water level stays there.

Before the water level gets too low, I see no air at all in the pump basket. After putting the vaccuum in, I do see a little bit of air.

So basically water level drops about 3/4 inch - 1 inch per day until it reaches a couple of inches above bottom of the skimmer inlet and stays there. Any thoughts?

Thanks!

 

[PoolGuyNJ]

When the water stops dropping, does air get in the system? I don't care about the vac hose, that's likely cavitation.

Scott

 

[Bama Rambler]

Where it stops is where you should start looking for the leak. Look all around the waterline. Inside the skimmer, any projections, etc.

 

[poolman10]

Thanks very much for your replies.

The water drops to the point where there's not enough water to fill the skimmer to keep up with flow and it starts sucking air. At that point, I hook up the vac hose just to keep circulation going.

After I put the vac hose in at aboout 11a yesterday morning, the water dropped another 1/4 inch when I checked at 8p last night (sun on the pool from noon until 3p yesterday, so doubt that 1/4 inch was due to evaporation). I turned the pump off, and when I checked this monring, the water level was the same.

I've checked all around the waterline and can find no leak. Only spot that intersects with the waterline is the skimmer and I tightened the plate screws on that yesterday morning. With the pump off, I dropped some food coloring in the skimmer last night and it did not move which makes me think there's no leak in the skimmer, though it could be a very slow leak.

I'm running the pump through the vac hose now -- will check the level in a few hours.

Thanks again.

 

[poolman10]

The level stayed pretty much the same throughout the day while circulating through the vaccuum hose -- may have lost less than 1/8th of an inch. We just had a good bit of rain, so I turned off the pump and will see where we stand in the morning.

 

[X-PertPool]

I would do a bucket test with the system running then another bucket test with the system off and winterization plugs installed into the skimmers and returns

if the loss remains the same from both tests then it's somewhere in the shell. If not then it's in the plumbing