Pebble Tec hairline crack repair

[Shieldsfx]

I've surfed the net for hours, including this site and haven't found a definitive answer to my quest to fix a hairline leak in hot tub section of my pebble Tec / SWG pool.

I've had American Leak find the leak since it was so slow and difficult to find. Once found I realized it is a 2 foot horizontal hairline leak. American was going to put the underwater two part epoxy over it but I held them off due to the stark white obvious line it would make. They told me to drain the hot tub and use 100% silicone. I was skepticle of how long silicone would last underwater in this application. It's a small leak 1/4 inch day sort of leak so I'm not interested in overkill and could easily drain hot tub to update repair every 2 years or so. By the way, the pebble Tec in my hot tub is smooth Grey and not the typical granular colored pebble Tec used (which I did use on the adjacent pool).

With that said, any suggestions for the material/epoxy I should use? Comments on the use of silicone?

 

[Shieldsfx]

Winter is approaching fast in the northeast so I decided to use the AB epoxy, to stop the leak before the cold sets in and I can decide later in the spring how to address this hairline crack from a cosmetic standpoint. The white AB epoxy was only available at the nearby store so I used that. As expected, it's not a sexy outcome for my gray pebble tec hot tub but it worked well to seal the crack (which I later found to be two different 2 foot cracks). I'll checking later to update on my success but I will decide later if I remove and use the grey AB epoxy, paint over the white or use an entirely different technique next spring.

Again, I welcome any suggestions to make my fix more "Perfect". I'll send pictures later ...

 

[pooldv]

My PB filled a crack in our black pebblesheen by mixing white epoxy and black epoxy to get a dark gray.

 

[duraleigh]

Epoxy is probably the best solution. That said, If you can find polyurethane caulk in a color that is acceptable, I would use that first.

 

[Shieldsfx]

UPDATE: the hairline crack that I patched using AB epoxy (see above) is leaking again, after 6 months. There are several small leaks at the edges of the epoxy (where the epoxy meets the Pebble Tec surface). I guess my options are: 1. try to seal the small leaks right on top of the epoxy, 2. remove the old epoxy and try again. Further, I wonder if the Epoxy is the best solution. American Leak Detection says put silicon first into the crack and then epoxy (or just silicone alone). Duraligh, above, suggests polyurethane caulk. Again, I have a gunite/pebble tec pool about 8 years old. The crack is in the corner of the hot tub (inside pool). I suspect ground settlement in that corner has cause this horizontal crack. Any suggestions here would be greatly appreciated...

 

[pooldv]

Bummer! Maybe some caulk first won't hurt. The leaking crack that my PB fixed with epoxy has held for about 3 years now. And we had a couple of new, non-leaking cracks in the same area that were epoxied last fall.

Add your location to your profile so it shows up over there <---

If you have black clay or expansive clay soil, like we do in DFW, setting up a micro irrigation system to maintain even soil moisture levels will help a lot. Most of my pool movement occurs when I don't water enough and the soil contracts. A gap develops around the edge of the pool. That is why it cracked again last fall. We had lots of rain last year and I didn't check soon enough and turn the irrigation back on in time. From 2012 to 2015 I had no issues with pool movement.

 

[Shieldsfx]

Poodv, I live in the northeast (updated my profile - thanks), but I think you are right about the soil holding up the area around the crack. I've included a picture and you will see a clear depression leading up to the corner of the pool. My thinking was the water leak may have caused the soil to erode, but it may also have been the soil erosion that caused the weight of that corner to break away, causing the hairline crack around that corner. Either way, I agree with your other point to at least caulk the around the AB Epoxy, areas that are leaking, for now. Eventually, I'm going to have to dig up that corner to sure it up, with stones, additional dirt, etc.

What sort of caulk would you suggest?
If I redo the AB epoxy (removing and reapplying) is this the best solution for gunite/pebble tec?

 

[gwegan]

Ok something is most likely going on here other than a hairline crack.

Its doubtful (but not impossible) a hairline crack could itself cause that much subsidence. Additionally its doubtful that the lack of soil support caused the weight of the water to crack the gunite shell. Generally outside forces cause pool shells to crack. But who knows here. Sometimes it just happens and you really are not sure of the cause.


I personally would excavate the area and see what is going on. I'd do that sooner rather than latter. Clearly what ever was happening before is continuing and will most probably continue until you do something. I suspect we can tell you to do X or do Y, but until you resolve the cause those will only be temporary patches and your leak will return.

 

[pooldv]

I agree that it might be time to do a little digging to see what is going on under there first.

But that may just be because it will cure underwater. Is your spa drained? When you say it is leaking is that because you see water leaking into the spa at the crack? Or how are you seeing a leak?

My PB always repairs pebbletec with AB epoxy. If you want to caulk I would use polyurethane caulk based on duraleigh's suggestion, I don't have a different answer. But, I think I would prefer to dig it out with a screwdriver or something and really jam the AB epoxy in there with your thumb. That is what my PB did.

 

[Shieldsfx]

I agree, I'm going to have to excavate but let me clarify and add a couple points. The "hairline" crack was quite long, about a total of 4 feet, wrapping around the corner (near that deck pole in picture), and about 1/4 wide after I cleaned it out for patching. The leak was greatly reduced after patching but still leaking about 10 gals/week (i've metered the flow). Another suspicious issue is the builder made a mistake in the hot tub seat height, and jack hammered it down (in that same corner) after gunite but before pebble tec. When looking at these factors, I believe their jackhammering (8 years ago) may have caused the crack, and later the pebble tec gave way in the area. I'll send construction pictures showing some of this and the area that I plan to excavate (in case you are interested). The builder was PEbble Pools in Royersford. I await their response, but frankly I don't expect much. More to come.

 

[pooldv]

Good info. That reminds me of some investigation we did. The crack from 4 years ago that leaked was 2-3 ft long, mostly on the face of the bench and up a few inches across the seat of the bench. The bottom drain line comes up that wall and under the bench right where the crack is. It also seems, as luck would have it, that is about the line where an underground caliche rock shelf takes a dive deeper underground. So, more clay soil to one side (2/3 of length) of the crack and more solid rock on the other (1/3 of length). It leaked enough to add a noticeable amount to the water bill, maybe 60-80 bucks, and the next month it was gone after patching. PB dug it out with a flathead and stuffed AB epoxy in the crack.

We subsequently, late last summer, had 2 or 3 cracks, or 2 longer ones, in the same area but, they did not leak, based on water bill and red dye tests. Same drill, flathead and epoxy.

PB said gunite flexes more than plaster so it is possible for the gunite to flex enough to crack the plaster. Your situation is different with it being at the end of the pool shell. It seems like digging, backfilling and compacting and the patching the crack with AB compound could solve your issue long term. I'm sure the pics will help tell the story better.

I don't think 10 gal a week is a leak. How did you factor for evaporation?

 

[gwegan]

I'd like to see the construction pictures and what you find after doing some excavation.

I don't think 10 gallons a week is a leak. Its within the margin of error even with a cover on.

I rather doubt that the jackhammering caused the leak 8 years later.

Just a guess but it may be you had high water in that area-- it froze over a couple of winters and caused a small leak in the gunite. So a combination of cold and outside water. Some force generally cause gunite cracks.

 

[Shieldsfx]

UPDATE:
I excavated. I attached a couple pictures, which only provide perspective. You'll see the hot tub crack which I had already patched. After investigating the hole, I found the PVC pipes for hot tub (suction and return) to be in good order. With such a small leak (20 gals a week), it seems that I would not find the pipes to be a problem. But the gunite side wall, where there hairline crack starts on the other side is quite moist along what a appears to be a crack in the gunite. I don't know if the gunite is supposed to be smooth along the exterior, but this area is clearly not. I'll try to take pics with bright light. Now, if this is in fact the leak, you would think an ink test along the patch inside the tub would show leakage? No apparent leaks after testing the entire 4 foot or so crack. I'm still opened up and investigating. Thanks to those tracking along.

 

[Shieldsfx]

Oh, the update on the gallons per weak. I've metered the pool line and calculated about 20 gals/week loss or nearly 3 gals per day. It's a SW pool, so the biggest hassle is carting 40 lb bags of sand to the pool each month!

 

[pooldv]

No gunite is not going to be smooth on the dirt side. I doubt a leak that slow would draw the dye to the crack. Get some pool putty, black and white, mix it to a close gray and "moosh" it into the crack in the Pebbletec. It will cure underwater and stop the leak if there is one there.

How are you factoring for evaporation? A typical pool can lose 1/8" to 1/4" per day to evaporation if sunny and/or windy.

 

[Shieldsfx]

The Saga Continues... The above posts outline my year long attempt to find a leak in my pool. The most recent activity include American Leak Detection, who did a complete test and determined there was a hairline crack in my hot tub, which was fixed. The leak continued. American Leak came out again, and continued to focus on hairline fix, but die tests were not confirming this theory. The leak is 20/gals per day (I put meter on the auto fill line). I tested with pump off and pump on, both tests leak the same. Interestingly, when I turn pump on (after 5 days being off), I get a ton of bubbles spewing out main returns for a few minutes. Remember American Leak pressure tested all plumbing. There's no leaks around my pool equipment maintained contained within an inside pump room. I feel like need to get another leak detector out, because ALD was not able to find it. Given the major symptom (the bubbles in main return), it seems obvious that the leak is in main drains. Any thoughts before I restart this whole process again? (visual inspection of pool shell, skimmer, visible equipment, etc. all look fine).

 

[pooldv]

1/8" of evaporation in a 15x30 pool is 35 gallons per day. So, 35-70 gallons per day is evaporation.

 

[Shieldsfx]

Pooldv, thanks for the response. I realize evaporation is part of this story, but seems high. I guess I need to do specific calculations for my pool, which is rather small. It's a 23'X13' pool, and inside that footprint is a corner hottub. Another key aspect of my findings is that I lose a 40 lb bag of salt per month (SWG pool). So, the significant bubbles from jets at pump restart and the salt loss per month are pointing to a leak. In addition, I checked the usual areas for air leaks around the pump, including the pump and filter and all seem very tight, showing no signs of excess air. It's a 10 year old pool and this apparent water/salt loss was not the case in the first 5-7 years; just the past 3 or so. I'll keep at it but appreciate further thoughts. Thanks again.

 

[pooldv]

Salt loss definitely points to a leak. The math seems off by a lot so I did some calculating in PoolMath. 20 gal per day is 600 gal per month. 40lbs of salt into 600 gal of water would result in nearly 8000ppm of salt in the 600 gal sample. 23x13x4 feet deep is about 9k gallons. If you start with 3500ppm of salt and add 600 gal of water and 40lbs of salt that would leave salt at a bit over 4000 ppm. Increasing salt by about 500 ppm every month. How are you measuring the salt ppm?

 

[Shieldsfx]

Very interesting approach to calculating the leak - based on salt loss. That seems like an easier path for me. My prior figures were rough calculations, so to be more specific my pool depth ranges from 6 foot to 4 (or say average of 5 foot depth), and the actual loss is more like 30 lbs/month of salt. Also, the average ppm of salt I maintain is 3100. And as you know, evaporation would account for some of the loss, which would require adjustment. I don't think I have all of your variables above to run a recalc, based on your approach? I give it more thought, but I wanted to send along these inputs. Thanks again for your thoughtful response.