Finding a Leak

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curlytop09

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Oct 12, 2013
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I've been suspecting that our inground gunite pool may have a leak. I searched this site and found the suggestion to do a bucket test. I have done two bucket tests. The first one indicated that there was approximately an inch difference over 24 hours between pool loss and bucket loss. I did a second test and over 36 hours had a 1-1/4" differential loss. First part of test was with pump off and then last with pump on. There didn't seem to appear to be a difference in water loss with pump on or off. The loss was about same over the two periods. My starting point for the test is halfway up the skimmer.

The reason I mention that is because since having the pool, we have noticed that when we get a hard rain and water reaches top of pool, it will not overflow. Once rain stops, the water will drop to mid skimmer rather quickly. Couple hours I would say. We bought house with the pool, have had 2-1/2 years, and assumed that was an overflow feature. We had the pool resurfaced 2 years ago and I can't recall if pool dropped in level like that before resurface. Being new pool owner, I was busy trying to keep water clear. I did mention it to the pool guy who did the work but he said it was normal. I believed him. But now I'm wondering if maybe connected. That large leak up in skimmer that may be propagating down some slowly.

Another suspicious area is the light. After resurface, I noticed water was getting in the light. We had the gasket replaced but I think toward end of last summer I saw water again.

My question for now is next steps. We are leaving for vacation tomorrow for 5 days. I feel uncomfortable leaving pool with pump to kick on daily and not sure if level will stay above skimmers. As much as I hate to leave pump off, I was going to turn off while we are gone. I thought this may be a good time to lower the level to below the skimmer and do a bucket test while we are gone. Any issues with doing that? Something else I should try?

Thanks for any suggestions
 
Almost out the door huh? Okay. And you're sure there is no overflow huh? Typically you'll find them along the waterline or in the skimmer itself. If not, then perhaps leaving everything off is best. When there's a leak, the water will settle-down to its point of escape then stop. So if the link was indeed related to the light fixture, then it should stop there. If you have an autofill feature, you'll need to disable it.

Before you go however, I would crank-up the FC to SLAM level and let it mix real good. Perhaps put a tab floater in there as well with a couple pucks for those 5 days. Try avoid any green monster when you return.
 
We do not have autofill. I have to manually refill when level drops.

I'm not 100% sure there is no overflow. I am 100% sure we lose about 2" almost immediately when Mother Nature fills to top or when I forget to turn water off. I have just lived with that and refill only to half skimmer level. There is nothing along the water line visible and nothing in skimmer that I can see when taking lids off that would allow water to drain that quickly. I can't see very well the area passing beneath the concrete. It's still too cold to get in water for a better look.

I have not done a dye test. Wanted to narrow down area to try test.

What would plunging returns do for leak? But no I have not tried that.

If I decide to leave pump off , would this be good time to rule out skimmer by dropping level below them ?
 
I think gwegan may have meant to type "plugged". :) That's one way to isolate some lines to help pinpoint where a suspected leak may be. Ruling-out the skimmer could be done a couple ways. A dye test perhaps by seeing if dye gets sucked into a spot along the inside edge of the skimmer. Problem is you can't see "under" the skimmer. If your water level keeps dropping below the skimmer, you know it was something else (i.e. light fixture). Leaving the pump off would rule-out a pressure side leak (pipes going to your return jets) more than anything since it would not be "pushing" water.

Since you're leaving soon, with probably not much time to spend on this issue, I would still increase the FC and keep a couple tablets in a floater. Turn the pump off for those few days and let the water settle. Where it stops will be a good indication of what's happening. If you come back and the water level hasn't changed at all (pump off), you can probably focus on the pressure-side returns as suspect. With the pump off, if the water level drops and stops at the light fixture, you can assume that's where your leak is.

Also when you return, perhaps post some pictures of the inside of your skimmer, pool, and any equipment that may help us look for anything unusual. Since you're not 100% sure of some items, we should try to help you to ensure you are 100% confident whether or not you have those items. At least we'll try. :)
 
Thanks for the tips pat. I think I have ruled out pressure side because I did leave pump off for 24 hours and had loss.

I will increase FC before leaving. May be able to get some plugs for skimmer before I go.

We got our kids a GoPro for Christmas. May come in handy for me. I may be able to use to see the area passing beneath concrete.

Thanks again
 
I think We've found the potential leak source. Looking closer at skimmer , there are some small cracks. Water level is right below that now. So if that's it , level will stop dropping. We can't leave for camping till tomorrow now so I can check tomorrow. Or fill back up and do dye test today. It's quite windy today and water is choppy so not sure if that would make test difficult.

Do skimmers have to be replaced when cracked or can the cracks be sealed with some type of resin.

I did find where large loss comes from after hard rain fills pool. On both skimmers , there is a gap between the concrete and top of skimmer weir. I do remember pointing this out to pool guy after resurface. He said was like that before and not a problem. So if no problem having , I won't address and just focus on the slow leak. Which I'm hoping we have found with the skimmer cracks.
 
I do hope you found the source. As for repairing, if it's just in the shell of the skimmer where you have access, you might be able to apply a sealant or epoxy since all it should be doing is "containing" the water before it goes down the suction plumbing. It's not really under pressure. You might have to just lower the water a little to have a dry area to work with. So think positive there. As for the other issue about water being allowed to seep between the skimmer and concrete, you might need to post a pic of that when you get back so some others can look. The main concern is allowing a substantial amount of water (over time) to seep between the pool shell and its supporting ground, and eventually spilling down to the base. You wouldn't want erosion to disturb the foundation of your pool area. At the same time, I wouldn't think overfilling is something that happens too frequently. Have a nice trip, and keep us updated when you get back.
 

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I think I've attached a picture of the large gap between skimmer and concrete. This is where we lose when pool is full after hard rain. I normally don't fill that high. If someone can comment on wether this can be an issue long term I would appreciate. I do not know if this has been there since pool built in 2003 or if after we resurfaced 2 years ago when we inherited pool.

I could not get a clear picture of the crack that runs down the skimmer. Camera wouldn't focus. It is a very fine crack and about 2-3 inches long. It may not even go through thickness of skimmer. I'll take closer look and try to get better pic when home and not raining.

I estimate the loss rate at approximately 10 gph. The crack may not be big enough to account for that amount.

Troubleshooting is on hold for 3 days. I've increases FC and turned off pump. Left bucket on steps and will see what level is when I get home.
 

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anywhere you suspect a leak, squirt a drop of red-food-coloring and watch the flow. Make sure that when you dispense it, all equipment is off and there is no wind. Also, you cannot disturb the water line as well...
 
I'm no tile/grout expert, but if I'm looking at your pic correctly, we're looking straight into the opening with the weir pushed down (fully open), and decking at the top ... right? If that's correct, then I would think that is a space you should consider filling this season. Reason being that unlike a true overflow, that space was not designed for such water flow, and anytime we allow water to continuously seep behind the structure or parts not designed for water, it can cause more problems later. A similar example would be along the top of the waterline/grout line edge where grout eventually fell-out. We wouldn't want water to be able to continuously spill into that opening between the pool shell and supporting soil.

When you get back, if your water/bucket level is the same, then that's a good thing. Some of the folks here can surely give you a tip or two on how to clean/prep that area, then what product (mortar, epoxy, etc) would be ideal to fill it in.
 
Pat,

Is there protocol to the bucket test?

If the bucket is filled only 1/2 or 3/4 full. I would argue the waterline in the bucket is not subject to strong wind currents which is a major contributor to water evap. Furthermore, if not placed in the sun that is an equal average representation of that the pool receives, that too has a major impact. Also, is the water used to fill the bucket from the pool or tap? If tap, then the chemistry is diff too. The bucket also does not have the water flow as the pool does when the pump and other is running.

Anyway, just trying to get a perspective how the set-up and protocol of a bucket test is conducted to ensure you are emulating the pools water conditions.

Thanks,
tstex

PS - water region of SC Tex you reside? We're in west Houston. Me and 15 other guys go on an annual fishing trip to Port Mansfield/Arroyo City and Baffin Bay. We actually skipped this yr for the first time in 20 yrs...Happy Easter
 
tstex, you bring-up some valid points. Probably a little more than even described on the LEAK DETECTION page. I suspect the more variables that are similar between the bucket and pool the better. It's not an exact science, but should give any pool owner a good basic idea of what's happening.

As for locale, I'm just outside of San Antonio, a little more in the country area. I'm not too far off of I-10 as it leaves San Antonio on its way to Houston. Last time I took a trip up there to see the Astros, I think it was about a 2 hour drive or so. Have a blessed Easter as well.
 
Pat - thanks so much for suggestion on getting gap fixed. I'm kind of disappointed that my pool guy that did the resurface work didn't see this as an issue. They are supposed to be the experts.

Tstex- for the bucket test , I filled up using pool water and up to within an inch of the rim to try and get same wind effect. I sat on steps in pool and it has about same sun exposure as rest of pool. I also kept pump off for 24 hours. There was almost an inch difference in loss between the pool and bucket. I also estimated what the evaporation losses would have been based the daily average conditions (temp, humidity , wind). The bucket losses were close to that. Not exact of course but enough to convince me what I saw is a true leak.
 
Fair enough Curly..seems you emulated enough of the pool waters characteristics in the bucket to make a conclusion.,,you could also set-up a control w another exact type of bucket, pool water and set in a more shady spot...if the bucket placed where you described above had less than the shady spot, then you could conclude your test w greater accuracy...not trying to be anal, but just want you to achieve the most accurate conclusion.

As you stated, I would contact your plaster company and have them come back and fix this problem, if it is indeed the issue....I should not take him long and you could pay him a little cash once the work proves valid...keep us posted Curly and good luck - tstex
 
Well, looks likes after a weekend away the pool level still dropped. Over the 4 days gone, level in pool dropped almost 2 inches. The bucket level dropped by slightly less than 1/2".

If water stays calm today, I want to try some dye testing. Any suggestions on best liquid to use. I've read that food coloring can disperse to quickly. I've read where some use the regents from pool kits. I just received by refill TF-100 kit. I have some old stuff that I was going to get rid of (R-008, R-0011L). Would that work? I also read some people make their own with cough syrup. And would I use a syringe to apply, not that I have one handy. Is this something the local pool store would have a kit for at 3x the price?
 
Bummer about that continuous leak. Sorry, I don't personally have any other leak detection tricks other than what you already mentioned or what people have tried in the "Search" feature. Be careful about the R-0011 though. I'm not positive, but I believe some of those reagents can actually stain some products. You might want to try a small test area first.
 
yikes, on the staining. Didn't think about that. I found some dye at the pool store that is fluorescent. I tried that on the returns and could not see anything indicating a leak. Same for the light in the area I could reach. I couldn't reach or see on the bottom end of the light so will wait till I can get some help. Thinking holding a mirror down below, if I can find arms long enough, will help see. The water in the skimmer area was moving too much to test today.

I may go ahead and plug off the skimmer and returns as well to completely isolate the pool. Well, except for the drain. Not sure how or if that can be done. I can't find a thread I read previously read on plugs NOT to use because may not be leak tight. Are plugs that are used to winterize pools sufficient? We don't winterize so I have nothing on hand and will need to purchase.
 

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