Locating a pressure side leak

[D-W-B]

After reading several informative (but closed) threads on pool leaks - particularly plumbing related ones - I am still in need of a little guidance on my next steps. Bucket test #1 - pump on elevated spa spillover on - pool lost 1.5” bucket lost less than 0.25” in 24 hours. Bucket test #2 pump off for 18 hours - no noticeable change in either bucket or pool level. My conclusion is that I probably have a pressure side leak that is only leaking when the pump is running. During the pump-off test the elevated spa drained to the level of the jets but no lower. I conclude that I likely have a faulty back flow valve (Jandy brand with clear front) but I am not certain of this.
I confirmed there is no water escaping the spider valve into waste when pump is running. No obvious signs of water on equipment pad area. I actually replaced the entire spider valve assembly on top of sand filter this summer. I bought but have not used a syringe with red dye / leak detection kit.

My thoughts on next steps:
1> Block all return jets in pool and spa and pressurize supply side at outlet from filter to pool - and confirm leak is on pressure side piping. Possibly listen for air/water/bubbles - possibly air leaking into / around the jet penetration (hoping the leak is very close to the entry for repairs). I have never done this or seen it done but it does not seem difficult and I have 20# CO2 bottle with regulator I can set to 5psi - 25+ and see what holds.
2> Cut apart PVC at filter and perform test above isolating spa and then pool - to pinpoint which jet plumbing side has the leak (spa or pool). Everything is glued for fast installation and not for diagnosis.
3> Call a pro

15,000 Gunite pool with elevated spa (6 jets pool, 2 Lilly pad, 6 spa)
Pool age 20 years +/-
Sand filter, gas heater, automation valves and Hayward Goldline controller
Salt water + generator
Auto fill (currently turned off for testing)
Auto drain on overflow (I blocked this as I believe the auto fill was incorrectly set and was filling down the drain every day)

Thanks in advance for any insight or even just confirmation I am on the right track??

 

[Texas Splash]

Welcome to TFP! One thing's for sure, not all leaks are created equal. I learned that in my recent experience (below). At some point, unless you get really lucky finding a leak, you'll call a leak detection company for assistance. There's no substitute for sensitive listening devices like deck plates or using a bore scope if needed. For now though, the more leg-work you can do to narrow down the potential leaky area the better. Not only will you appear to be educated about your system, but it may save some time & money as well. If you have a way to bypass some of the return plumbing to isolate it for evaluations, that's great. In my case I could not. All of my 6 returns are fed from one main return line then they "T" and split from there. In my case, there was no indication of a pressure side leak at the soil's surface. I guess the water just dribbled/flowed downward into our gumbo clay soil. Good luck on your leak detection. If you have more questions let us know.

Leak Detection (Pressure Side), Results, and Frankenplug

After 9 years it finally happened – the dreaded leak. Here is my story. In the San Antonio area we have black clay soil that is horrible for structural support of any kind and often causes problems for home foundations, fencing, asphalt, pools, etc. When we observed excessive water loss, I...

www.troublefreepool.com

 

[Jimrahbe]

D,

A lot of pressure lines are all connected together underground. As an example, all your pool returns are most likely connected together.

So, I would try to run things that you can control..

Run just the spa and no spillover and see if it still leaks or not. In the spa mode all the pool returns should be off.

Then try running just a waterfall or water feature by itself. Etc..

If you can run everything except your pool returns and you don't have a leak, then you know the problem is in one of the pool returns. At that point, you will have to call a leak detection company who has the equipment to locate the location of the leak.

Thanks,

Jim R.

 

[D-W-B]

D,

A lot of pressure lines are all connected together underground. As an example, all your pool returns are most likely connected together.

So, I would try to run things that you can control..

Run just the spa and no spillover and see if it still leaks or not. In the spa mode all the pool returns should be off.

Then try running just a waterfall or water feature by itself. Etc..

If you can run everything except your pool returns and you don't have a leak, then you know the problem is in one of the pool returns. At that point, you will have to call a leak detection company who has the equipment to locate the location of the leak.

Thanks,

Jim R.

Thank you Jim! I’ll start isolating and testing to narrow down the culprit!

 

[D-W-B]

Welcome to TFP! One thing's for sure, not all leaks are created equal. I learned that in my recent experience (below). At some point, unless you get really lucky finding a leak, you'll call a leak detection company for assistance. There's no substitute for sensitive listening devices like deck plates or using a bore scope if needed. For now though, the more leg-work you can do to narrow down the potential leaky area the better. Not only will you appear to be educated about your system, but it may save some time & money as well. If you have a way to bypass some of the return plumbing to isolate it for evaluations, that's great. In my case I could not. All of my 6 returns are fed from one main return line then they "T" and split from there. In my case, there was no indication of a pressure side leak at the soil's surface. I guess the water just dribbled/flowed downward into our gumbo clay soil. Good luck on your leak detection. If you have more questions let us know.

Leak Detection (Pressure Side), Results, and Frankenplug

After 9 years it finally happened – the dreaded leak. Here is my story. In the San Antonio area we have black clay soil that is horrible for structural support of any kind and often causes problems for home foundations, fencing, asphalt, pools, etc. When we observed excessive water loss, I...

www.troublefreepool.com

Thank you Texas - very valuable post on your own leak problem and solution!! I’ll continue to evaluate potential leak as far as I can. Appreciate your reply so much!!