Leak has me Stumped

[Flynn713]

Hi everyone,
Our in ground pool has a leak whenever our pump is running using the skimmer line. Our latest test showed 1/2 an inch in 10 hours. We tried isolating the leak by shutting off the pump and plugging all return lines and we did not lose any water. When we run the pump using the bottom drain line we do not lose any water, either. We thought we had a leak in our skimmer line, but all my lines were pressure tested and they all held 20 psi. I have been getting a small amount of air bubbles in the pump when we run our vacuum on the skimmer line, but it seems to disappear if I blend the skimmer line with the bottom drain line (maybe like 80/20 or so). Anyone had a similar experience? Any suggestions on what I should do next? This is my first post, sorry if I left any information out. Thanks in advance!

 

[JohnT]

Welcome to TFP!

Your results are perplexing. It shouldn't matter where you draw the water if it doesn't leak with the pump off.

Have you checked your waste line for water while your multiport is set to filter?

 

[Flynn713]

Hi John,
Thanks for the quick reply. As I am new to pool ownership, maybe I am not describing the issue accurately. I can run my pump with the intake valve set at all skimmer, all bottom drain, or any mix in between. We only seem to lose water when the skimmer line is being used. All bottom drain and we don't lose water.

I only hook up my waste line when we are backwashing, rinsing, or vacuuming directly to waste, so it would be obvious if we were losing water through the filter. Any thoughts on how water could be lost only when the skimmer is on?

 

[JohnT]

Hi John,
Thanks for the quick reply. As I am new to pool ownership, maybe I am not describing the issue accurately. I can run my pump with the intake valve set at all skimmer, all bottom drain, or any mix in between. We only seem to lose water when the skimmer line is being used. All bottom drain and we don't lose water.

I only hook up my waste line when we are backwashing, rinsing, or vacuuming directly to waste, so it would be obvious if we were losing water through the filter. Any thoughts on how water could be lost only when the skimmer is on?

I'd suspect the drain plumbing, except you say it didn't leak with the returns plugged and the pump off. Sometimes suction lines only leak when they aren't being used. With full suction of the pump on the drain it pulls the crack together it quits leaking. Quit drawing 100% from it and the crack opens and water leaks out. But water should leak the same with the pump off if that was the issue.

As I said above, the results seem to contradict each other. What do you lose with everything off and nothing plugged?

 

[Kiss4aFrog]

Welcome to the forum

 

[Flynn713]

I'd suspect the drain plumbing, except you say it didn't leak with the returns plugged and the pump off. Sometimes suction lines only leak when they aren't being used. With full suction of the pump on the drain it pulls the crack together it quits leaking. Quit drawing 100% from it and the crack opens and water leaks out. But water should leak the same with the pump off if that was the issue.

As I said above, the results seem to contradict each other. What do you lose with everything off and nothing plugged?

I will measure the water loss with the pump off and nothing plugged tomorrow and report the results.

 

[DogsHouse_MyPool]

I've had similar issues with leaks in the past. I went so far as to do a dye test to try to locate the problem, which came up negative. My issues ended up being air leaks on the pump pad. My pad is concrete, so the first thing I would look for is any water what so ever on the pad. I have since redone all the pad plumbing and have no more air leaks.

I still have what I would call high water loss in the top inch of the pool. I've been watching it close this week, and I am a little perplexed too. I lose about 1/2 inch water per day, with the pool full to overflow. After about 1 1/2 inches of loss, I am losing what appears to be less than 1/4 inch per day to evaporation. Rain and clouds makes it difficult to pinpoint. I've inspected all my tile, and I don't see an issue. It is perplexing. I hope you get to the bottom of the problem. I'm going to watch in case there is a dejavu moment here.

 

[Flynn713]

Hi Doghouse, I don't think it is a leak on my concrete pad as I never have water there. All my fittings & connections were replaced last week when the company did the pressure test and I had the leak before and after. I am in the process of bringing my water up before I shut off my pump and see if I lose any water as per JohnT's suggestion. Thanks.

 

[Flynn713]

Ok, I brought water level up to our "normal" fill level. I shut off pump and plugged the skimmer line. I have lost about 1/2 of an inch of water in the first 6-8 hours, but then the water loss definitely seems to slow down to the point where it is only about 1/8 of an inch over the next 16 hours. Some questions:
1. Since the water loss occurs with the skimmer line plugged (and it passed the pressure test), does that mean I can rule out the skimmer line as the source of my leak?
2. Can water loss occur from the bottom drain even with the pump off?
3. What does it mean if I lose a lot of water initially, and then the water loss slows? Is it because with more water in the pool, there is more pressure on the water in the drain, and it forces a crack open?
4. How do I leak test the bottom drain without scuba gear? Thanks in advance for any help or suggestions!

 

[JohnT]

Ok, I brought water level up to our "normal" fill level. I shut off pump and plugged the skimmer line. I have lost about 1/2 of an inch of water in the first 6-8 hours, but then the water loss definitely seems to slow down to the point where it is only about 1/8 of an inch over the next 16 hours. Some questions:
1. Since the water loss occurs with the skimmer line plugged (and it passed the pressure test), does that mean I can rule out the skimmer line as the source of my leak?
2. Can water loss occur from the bottom drain even with the pump off?
3. What does it mean if I lose a lot of water initially, and then the water loss slows? Is it because with more water in the pool, there is more pressure on the water in the drain, and it forces a crack open?
4. How do I leak test the bottom drain without scuba gear? Thanks in advance for any help or suggestions!

1. That depends on your plumbing.
2. Absolutely it is always full of water to the same height as the pool water level.
3. Probably that the leak is very near your water line. I don't think the pressure change is enough to make a difference. A crack in a step, a pipe or tear in the liner at that level are possibilities.
4. The drain cover usually has two screws. It helps to have a weight of some kind sitting on the bottom to hang onto while removing the screws. Wouldn't hurt to have a helper as it's tiring. Make sure the pump is off when messing with it.

 

[Flynn713]

1. That depends on your plumbing.
2. Absolutely it is always full of water to the same height as the pool water level.
3. Probably that the leak is very near your water line. I don't think the pressure change is enough to make a difference. A crack in a step, a pipe or tear in the liner at that level are possibilities.
4. The drain cover usually has two screws. It helps to have a weight of some kind sitting on the bottom to hang onto while removing the screws. Wouldn't hurt to have a helper as it's tiring. Make sure the pump is off when messing with it.

Ok, I've refilled the pool and have plugged the skimmer and my returns lines. I am going to watch for water loss over the next 24 hours to determine if I continue to lose water with the returns & skimmer plugged. I will also try getting down to the drain to perform a leak test. Thanks John. Anything else I should do?

 

[Flynn713]

Ok, I've refilled the pool and have plugged the skimmer and my returns lines. I am going to watch for water loss over the next 24 hours to determine if I continue to lose water with the returns & skimmer plugged. I will also try getting down to the drain to perform a leak test. Thanks John. Anything else I should do?

After 24 hours the water loss is the same, about an inch. The skimmer line was plugged as well as all the return lines.

I did not perform a leak test on the bottom drain yet as I had difficulty staying down there long enough to remove the cover and squirt the food colouring.

I'm checking the seals around the stairs and attempting to tighten all the screws that keep the liner attached on both sides of the stairs, but nothing seemed loose. What's next?

 

[JohnT]

After 24 hours the water loss is the same, about an inch. The skimmer line was plugged as well as all the return lines.

I did not perform a leak test on the bottom drain yet as I had difficulty staying down there long enough to remove the cover and squirt the food colouring.

I'm checking the seals around the stairs and attempting to tighten all the screws that keep the liner attached on both sides of the stairs, but nothing seemed loose. What's next?

I think you need to test your drain. You MIGHT be able to restrict the flow enough by putting a small sheet of plastic over it and putting a rubber feed pan like http://www.google.com/url?url=http:...6v7QpQ&usg=AFQjCNHrhGpEwqCLklNxBO4AV6FoNYGU3w with a weight on the top to cover the drain. No guarantee though. If you do that and see a reduction in the leak, you can probably start thinking it's the drain.

 

[Flynn713]

I think you need to test your drain. You MIGHT be able to restrict the flow enough by putting a small sheet of plastic over it and putting a rubber feed pan like http://www.google.com/url?url=http:...6v7QpQ&usg=AFQjCNHrhGpEwqCLklNxBO4AV6FoNYGU3w with a weight on the top to cover the drain. No guarantee though. If you do that and see a reduction in the leak, you can probably start thinking it's the drain.

Ok John, thanks for the suggestions. I will try to get down and leak test the drain with food colouring or by covering it up as per your suggestion. I'll keep you guys posted.