So, using your method of calculating the leak amount based on salt loss, I've updated the calculations. Pool volume is 23x13xx5x7.5 = 11,200 gals. Salt requirement for that volume at 3400ppm is 312lbs or about 8 bags (using pentair salinity calculator). So that's .028 lbs per gallon. I'm losing 20 gals/day or 7300 gals/year. Let's say 1300 of that is evaporation. That leaves us with 6000 gals loss/year x .028 (lbs salt) or 168 lbs, requiring four 40lb bags salt per year. This is less than what I seem to be requiring per year. This confirms your result above. I have not kept exact bag counts on salt use but I'm certain it's more than 4/year. My pool requires at least 4 when I open up in spring. Despite these irregularities, the salt loss is pointing to a leak.
Pebble Tec hairline crack repair
- Thread starter Shieldsfx
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Yes, salt loss points to a leak, splash out or overflow. And nobody is swimming these days. Interestingly, 1/8" in a 23x13 pool equals 20 gal per day. 1/8" evaporation per day is completely normal. So, who is stealing the salt and how are they doing it? 
How are you testing salt level?
How are you testing salt level?Funny. Yes, it must be a salt thief. And interesting your evaporation theory equals my daily loss. I'm measuring salt needs using gold line SWG equipment. It responds immediately when I add salt, yet gradually goes down overtime along with water loss. I'm going to plug up drains one by one to see if that reduces the water loss. More on this dilemma after that test. Thanks for hanging in there on this saga.
Update: so I'm back on the trail of this nastily little leak. Since I've thought it was the hot tub drain all along, I've decided to plug the drains and wait. After day one, no leak. Day two, no leak. After 1 week, just a few gallons, and not the 10 or so gallons I was getting daily! I'm on to something here. Finally. I'll continue my testing but now interested in how one goes about fixing a leak in a drain of hot tub within an in-ground pool?
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Sent from my iPhone using Tapatalk
Speaking generally, if you have a leak in the pool or built in spa drain you should be getting some air in your pumps leaf basket and will generally be producing some bubbles from the returns. That's because pool and spa drains are not really drains they are suction ports. So generally if they have leaks, especially near the surface they not only release water when the pump is not on but pull in air when it is on. Additionally they also can cause the pump to lose prime. Now note this was all stated generally because they don't have to do this but any of these symptoms may act as confirmation of your theory.
blakeusa
In The Industry
Bubbles in the return line when you start up is definitely a sign of (at a minimum) air getting into your plumbing system loop. This does not mean you have a leak where its losing water. In theory if your system was pressure tested you should have seen this loss of pressure....
I would plug all the returns in the spa - and make sure the pool and spa are level with water... and wait a few days or so to see if the spa is in fact lower than the pool. You can also place a bucket in the spa and make the water in the bucket the same as the spa.. and see if the spa looses water. With that amount of loss you should see moisture / dampness on the exterior wall where you excavated the area-- in the same area as the crack.
Air in the return line seems more like a plumbing leak than cracked 8 inch plus gunite + pebble tec, but thats just my opinion.
I made my pool in CT solid 12" + thick walls as many builders can save $$ shooting thinner walls and putting a "12 inch T" on top for the coping.
I gotta say something about jackhammering the gunite out of the spa seems like it would have made the walls thinner in those areas... do you know how much they had to cut out? ... say the walls were 8 inches thick to start and they removed 4 inches that would mean your spa is only 4 inches thick in some areas...
So to summarize;
1 - try plugging the spa returns (to make sure you are not having a return plumbing leak) and to stop new water from entering and do the bucket test. You can test the spa drains too as noted below.
This should isolate a true crack or seepage issue in your spa.
2. - do the same with only the pool return in the spa (overflow) plugged and do the same.. if your leaking now and not before there is a leak in spa the plumbing..
3. Plug all the returns and drain spa drains (plug spa drains) and refill spa with sump pump and see if you are leaking now.
Do you get any air or bubbles in your pump basket (if so then you have a suction or possible spa drain) problem.
If no bubbles in pump basket you may have a leak in one of the spa returns... or at the filter, heater etc (were it is sucking in air)
when the system is sitting idle. Under pressure it would then be leaking vs sucking in air.
Report back or new info you have.... leaks and redoing old plumbing sucks..
B
I would plug all the returns in the spa - and make sure the pool and spa are level with water... and wait a few days or so to see if the spa is in fact lower than the pool. You can also place a bucket in the spa and make the water in the bucket the same as the spa.. and see if the spa looses water. With that amount of loss you should see moisture / dampness on the exterior wall where you excavated the area-- in the same area as the crack.
Air in the return line seems more like a plumbing leak than cracked 8 inch plus gunite + pebble tec, but thats just my opinion.
I made my pool in CT solid 12" + thick walls as many builders can save $$ shooting thinner walls and putting a "12 inch T" on top for the coping.
I gotta say something about jackhammering the gunite out of the spa seems like it would have made the walls thinner in those areas... do you know how much they had to cut out? ... say the walls were 8 inches thick to start and they removed 4 inches that would mean your spa is only 4 inches thick in some areas...
So to summarize;
1 - try plugging the spa returns (to make sure you are not having a return plumbing leak) and to stop new water from entering and do the bucket test. You can test the spa drains too as noted below.
This should isolate a true crack or seepage issue in your spa.
2. - do the same with only the pool return in the spa (overflow) plugged and do the same.. if your leaking now and not before there is a leak in spa the plumbing..
3. Plug all the returns and drain spa drains (plug spa drains) and refill spa with sump pump and see if you are leaking now.
Do you get any air or bubbles in your pump basket (if so then you have a suction or possible spa drain) problem.
If no bubbles in pump basket you may have a leak in one of the spa returns... or at the filter, heater etc (were it is sucking in air)
when the system is sitting idle. Under pressure it would then be leaking vs sucking in air.
Report back or new info you have.... leaks and redoing old plumbing sucks..
B
blakeusa
In The Industry
Also LIGHT NICHES and the associated PVC electrical feed lines can leak too...
The light has grey PVC running to it and in under the water level. The cable is inside the PVC.
They can get water in this line if the silicone leaks and because they are not winterized -- & break or crack.
Normally they are sealed with plain 100% silicone seal.
To fix this or to eliminate this drain the spa.
Remove the light (one screw).
Push as much clear 100% silicone seal into the back of the niche where the electrical cable enters and make sure its all sealed up.
Reinstall light
Refill spa.
A pool leak company would not find this leak -- as it is NOT part of the pool plumbing.... and not under pressure.
BUT this would cause you to loose water from your spa or pool.
B
The light has grey PVC running to it and in under the water level. The cable is inside the PVC.
They can get water in this line if the silicone leaks and because they are not winterized -- & break or crack.
Normally they are sealed with plain 100% silicone seal.
To fix this or to eliminate this drain the spa.
Remove the light (one screw).
Push as much clear 100% silicone seal into the back of the niche where the electrical cable enters and make sure its all sealed up.
Reinstall light
Refill spa.
A pool leak company would not find this leak -- as it is NOT part of the pool plumbing.... and not under pressure.
BUT this would cause you to loose water from your spa or pool.
B
I appreciate the feedback. I had previously confirmed (through American Leak Detection) that the leaks are not on the pressure side (jet related), although they also tested the drains and said they were not leaking. As per my prior posts above, I had also confirmed that I was losing salt at about 1 bag per month (as I have a salt water pool), clearly indicating a leak. Despite Americal Leak's results, I was confident that the leak was in the drains, as there are a significant amount of bubbles that release when I turn the hot/tub pool on. So, I plugged the skim basket first, leak continued (I metered the connection showing 15 gals per day leak. Then I plugged the hot tub drains and the leak was substantially reduced (evaporation is a part of the metered results). I am now certain there's a slow leak in the hot tub drains. I will test the pool drains next, but have at least narrowed the field of possible leaks. The question is: how does one go about fixing an in-ground drain leak?
blakeusa
In The Industry
The only way to real fix a leaking drain is to dig it up and replace it. That involves jackhammering out the bottom of the spa where the drains are if that is the location of the leak. Its a big messy job - so you need to be 100% sure that is where the leak is and not in the line that is coming from the drains where it is below water level.
There may be a temporary fix if you can isolate exactly where the leak is- say a crack in the drain housing and glue and reinforce it with
a splice of PVC.
Normally a small crack in a pipe does not leak much unless it is under pressure.
And if your spa drain is leaking you should definitely be getting air bubbles (a fair amount) into your pump basket.
But you said the pool company leak tested your pool and found no leaks. I would re-test just the spa drains.
Also did you check your light niche.. they can leak too.
There may be a temporary fix if you can isolate exactly where the leak is- say a crack in the drain housing and glue and reinforce it with
a splice of PVC.
Normally a small crack in a pipe does not leak much unless it is under pressure.
And if your spa drain is leaking you should definitely be getting air bubbles (a fair amount) into your pump basket.
But you said the pool company leak tested your pool and found no leaks. I would re-test just the spa drains.
Also did you check your light niche.. they can leak too.
I agree. I should have drains pressure tested again. I have to be certain before I do anything radical. Thanks for the good advice.
Final Update regarding my mysterious pool leak: I had another leak test performed by Statewide Inspection. (Remember American Leak performed first test w/o success). Upon visual inspection he said: pool and plumbing look good. I believe it’s around your skimmer (where pool and skimmer meet); it has no putty, which would normally be done in construction and I’m surprised your prior leak detection didn’t see that. He then Performed all inspections and pressure tests, with valves removed. Results: Returns fine. Drains fine. Lights fine. He did note that pool valves and backflow values needed replacement, but they would not cause leak. Pool shell fine, including area I repaired in hot tub. So, back to skimmer. He put AB putty around the skimmer Opening connected to pool. After a couple weeks — Fixed! The two year ordeal ended up being a problem that explains 90% of all pool leaks - the skimmer. Too much attention was placed on inside the skimmer but not enough on the skimmer opening to the pool (which is hard to see and test by the way). Interestingly, I found another small leak in the automatic vinyl pool cover. This small hole sat under my pool cover pump, so the pump was dutifully removing salt water that pushed to the surface, because of the weight of the pump itself. I moved the pump until I can patch. Lastly, I found a very small drip leak on PVC pipe leading to my heater in Pump room, which may explain some of the bubbles I was seeing on pool startup. I found this by setting pump pressure on high and watched all pipes for 5-10 minutes. I need to replace valves and backflows at some point. Thank you to those that have been tracking along and hope this tread helps others.