Help a relative newbie (but oh so willing) diagnose a very recent pool leak

[FoothillTom]

Hello brethren and sistren, please let me thank you in advance for any assistance. Some background if it helps...

30,000 gal in-ground, easily 35 years old, concrete pool in Northern Cali
Built-in spa (not used), aging tile (have replaced dozens)
1 Skimmer, 2 drains, 2 returns (I think), but honestly I have questions about this
5 year old main pump, pressure pump for cleaner, pump for waterfall feature
2 lights, Jandy motorized valves to switch betwixt pool and spa
Programmable timer for adding water

Quite recently: water level began lowering way out of whack relative to evaporation. My carefully thought out refill algorithm was not keeping pace. Water level down just below skimmer inlet (more on that). Air in system, pump not moving water. Difficulty priming system, but eventually primes if I stay with it. Loses prime the next day.

Equipment is off. Running bucket test for 2 days so far. Pool is outpacing evaporation substantially (1/16" evap compared to 1/2" loss in 12-hour period)
Plan to keep running bucket test until water level stabilizes with evaporation (or I figure this out).

Did my own "dye test". Pool is really cold so didn't test drains (yet), but every other fixture shows no sign of leak. Which brings me to the Skimmer...

The Skimmer "inlet" is tile/grout. It's pretty beat up, definitely some gaps in the grout (will post pic tomorrow). The skimmer itself does not appear to have any fractures, cracks, on careful examination, but the area that leads to the skimmer (is that called a grotto?) has my attention.

I put some dye near the drain holes at the bottom of the skimmer and no movement. Ran dye test near the transition from the tile grotto to where the weir door hinges are located and it "may" have disappeared after a few seconds. It's really hard to see in there because the tile is blue and it was getting sort of late in the afternoon. The dye certainly did not race any one direction, I just noticed that it seemed to dissipate a lot quicker than any other test I ran and it didn't just lazily flow around like the other tests.

With all this as description/analysis, I'd like to ask some dumb questions:

1. If the leak is occurring structurally at the transition of the inlet/grotto to the skimmer, would that mean the water level should "stabilize" (consistent with evap) once the level reaches just below the inlet?

2. Would this type of leak explain the loss of prime? I can hear my filter "draining down" when I turn off the pump (glug, glug sound). Maybe I should just focus on the leak, but wanted to give as much info as possible.

3. I do not have separate lines coming to the pump from the skimmer and drains, just one for the "pool" and another from the spa. Is this considered bogus plumbing? I was hoping to be able to shut off suction from the skimmer as a test, but maybe older pools lake this feature?

4. I'd like to provide photos of some of the stuff on the side walls and two mystery holes near the deep end of the pool that I honestly cannot identify. What I believe are the drains have square plastic covers with slits, but these two mystery holes are just that: holes. Maybe 3/4" diameter holes with no cover. Wondering what the heck those are. There are similar style holes on the side walls which I believe put out water from the heater (based on sitting near them and feeling the warmth once upon a time).

Dang, this is a lot. I hope I didn't ruin my chances of getting good advice by boring you to tears. Trying to be complete. I really appreciate any thoughts on how to proceed. I've watched probably 50% of the contents of Youtube trying to find wisdom, but I'm still scratching my head.

Thanks!!!
Tommy D

 

[newdude]

With all this as description/analysis, I'd like to ask some dumb questions

I see 4 questions that are SMART because you asked them. They're only dumb when you don't ask them. Just sayin.

1. If the leak is occurring structurally at the transition of the inlet/grotto to the skimmer, would that mean the water level should "stabilize" (consistent with evap) once the level reaches just below the inlet?

Yup. Wherever the pool stops draining is the level you need to scrutinize.

2. Would this type of leak explain the loss of prime?

No. Not unless the skimmer was running dry from being very low.

I can hear my filter "draining down" when I turn off the pump (glug, glug sound).

This means air is getting into the system. Stick a straw into a full glass and put your finger over it and lift it out. That water will stay in there forever. Until you wiggle your finger (leak) and air gets in there for it to glug glug out. It could point to a plumbing leak on the return side. (The suction side wouldn't lose water, it would suck air and make bubbles). It could also be something silly like the pump lid gasket needing lube that has nothing to do with the leak.

Maybe I should just focus on the leak, but wanted to give as much info as possible.

We are only as good as the info we get, so more is always preferred.

3. I do not have separate lines coming to the pump from the skimmer and drains, just one for the "pool" and another from the spa. Is this considered bogus plumbing? I was hoping to be able to shut off suction from the skimmer as a test, but maybe older pools lake this feature?

Do you have 2 holes in your skimmer ? One to the drain and one to the equipment pad ? If not it's probably T'd just below the skimmer. Both are common in older pools.

4. I'd like to provide photos of some of the stuff on the side walls and two mystery holes near the deep end of the pool that I honestly cannot identify.

We LOVE pictures. Upload away.

 

[FoothillTom]

Thanks for help so far! Answering your question:

Do you have 2 holes in your skimmer ? One to the drain and one to the equipment pad ? If not it's probably T'd just below the skimmer. Both are common in older pools.

Yessir. I'll attach a photo of the bottom of the skimmer to confirm. If the T is underground, it's clear that I won't be able to run a suction test effectively shutting off the skimmer side of the house. Plugging the skimmer with threaded plugs would seem to have limited value for isolating the leak. Do you agree? I know those plugs exist, but maybe you could explain how they may or may not help me diagnose my issue.

I'm going to continue my thread below with some additional photos, but wanted to get clarity on what I see is an inability to rule out skimmer and/or drain since I can't isolate one circuit from the other with my plumbing setup.

Thanks again.

We LOVE pictures. Upload away.

 

[FoothillTom]

Continuing my tale of woe (but this time with photos).
@24 hours: bucket loss 1/8", pool loss 1/2"
@48 hours: bucket loss 1/4", pool loss 1 1/16"

Water level @ 48 hours is just at/below skimmer opening (see photo). My suspicions are growing around the skimmer connection to the pool. I've taken a few close-up pix and maybe those will help you confirm that this is a likely suspect.

The water level has not stabilized yet, but I think tomorrow will tell the tale if it is my skimmer connection.

I'll post another message here about the mystery of my various returns and holes in my pool.

 

[FoothillTom]

Clarifying what I said in my original post about the various gizmos in my pool. I've take a few photos to illustrate what I'm talking about.

1. In the "deep end" photo, I believe A and B are drains. The hole with the "?" is the mystery. There is a hole just like this out of frame on the right side of the drains.

2. In the "side of pool" photo, there is this hole which definitely has warm water coming out when the heater is running (which is rare). What is this called? A return?

3. In the photo showing the skimmer entrance, there are two gizmos "C" and "D". Are these drains? Side drains?

Thanks for everything! Appreciate thoughts and suggestions while I await the next day of water droppage.

 

[mknauss]

A and B are the main drain suction ports. C and D are the waterfall pump suction ports.

The mystery hole, does it have flow when the main pump is running? Is the 'opposite of skimmer' return only on when the heater is on? The one in the floor may be the same. Post pictures of your equipment pad and what you believe the lines/valves do.

 

[newdude]

From your skimmer pic, it looks like the 2nd hole which would go to the main drain is plugged. Have you ever felt the drains working to confirm they haven't been abandoned ?

 

[FoothillTom]

A and B are the main drain suction ports. C and D are the waterfall pump suction ports.

The mystery hole, does it have flow when the main pump is running? Is the 'opposite of skimmer' return only on when the heater is on? The one in the floor may be the same. Post pictures of your equipment pad and what you believe the lines/valves do.

Ah...ok, I had no idea the water fall had their own ports. Makes sense now.

As for the mystery hole, I've never taken the time to notice and now the pool is pretty frigid. I think a wetsuit is in my future before the end of this little saga, so I will confirm how that is behaving under pressure.

Regarding "opposite of skimmer" returns, sadly, I only noted the warm water coming out when the heater was on because it was warm. I've got no memory of how it behaves with just the pump running but that's easy enough to prove when I'm done with my multi-day leak/bucket test. I

I'll post a pic or two of my plumbing setup and maybe that'll tell the tale.
Thanks very much for taking the time to respond.

 

[FoothillTom]

From your skimmer pic, it looks like the 2nd hole which would go to the main drain is plugged. Have you ever felt the drains working to confirm they haven't been abandoned ?

Dang, you're right. It is completely blocked. This seems like a "stop the presses" kind of a moment. Does this imply that the main drains are not connected to the pump if the drain line TEEs into the Skimmer area (as was apparently common in old pools)?

This is hard for me to believe as I am quite certain I had lots of water pulling through the pump when the skimmer was in the closed position (the float valve was closed) but I'm not in a position to run that test for a day or two while I do a suction leak multi-day test.

Would there be any design reason why a skimmer would have two ports but one of them blocked? I have no history with the pool before 7 years ago, sadly.

This seems important. Would love to get your thoughts on this. Will most definitely be doing a dye test with the pump on at the drains when I can get a wetsuit.

The plot thickens, but this seems unrelated to my current leak situation.

 

[newdude]

Would there be any design reason why a skimmer would have two ports but one of them blocked? I have no history with the pool before 7 years ago, sadly.

If it's sealed from the factory, they only needed one leg. They likely would have used both holes originally instead of splicing the drain line to the skimmer line underneath.

If the skimmer only had one hole, then they would have had to splice it underneath, but that's not the case.

So your drain line is likely there in the skimmer, but abandoned and plugged. You would want to also confirm a good plug inside the drain itself. There may be a 20 year old rubber plug down there that's now leaking.

Keep us posted.

 

[FoothillTom]

If it's sealed from the factory, they only needed one leg. They likely would have used both holes originally instead of splicing the drain line to the skimmer line underneath.

If the skimmer only had one hole, then they would have had to splice it underneath, but that's not the case.

So your drain line is likely there in the skimmer, but abandoned and plugged. You would want to also confirm a good plug inside the drain itself. There may be a 20 year old rubber plug down there that's now leaking.

Keep us posted.

Thanks again for the good info. FWIW, my leak tests are now going into day 5 and the water level has gone substantially below the skimmer entrance. This is a bummer as I was really hoping for a relatively simple explanation and a pretty simple repair. The pace of the leak has come down a bit, but it's still waaay above evaporation. Here is a little graph of the loss over 5 days:



I'm going to locate a wetsuit and get a syringe/dye and attempt to find the leak. You've given me some hope that it could be a failed plug in one of the drains.

Updates to come, but please feel free to add any thoughts or experiences that you might think relevant.

Thomas

 

[FoothillTom]

I'm going to start a new thread as the situation on the ground here is substantially different from where we left our hero. I don't want to bore everybody with the whole story, so I'll start up a new thread asking a crucial question on solving my leak in the best way possible.

Thanks for the help so far (for anybody that may be reading this).

 

[mknauss]

I'm going to start a new thread

Keep it all here.

 

[FoothillTom]

Will do. So here is a succint of a story as I can tell before I get to my crucial questions.

Turns out, I think I have two separate leaks:
1. Pool leaking out to my unused built-in spa (which is covered by a deck, hence didn't know this was happening until looking the other day)
2. Skimmer has several gaps where it connects to the side of the pool and I suspect water is leaking from there as well

And just for background, it appears the previous owner abandoned the drains as my pump only moves water when the level is above the skimmer. I can only surmise that the drains leaked and they somehow capped them off. I have a wetsuit which I plan to peel on tomorrow to verify the behavior of the drains, but I'm 99% sure my skimmer is the only suction from my pool.

Regarding Leak #1:

Some moons ago, I officially abandoned the built-in spa. We didn't use it at all for warmth and the plaster was frankly becoming a disaster. I drained it and thought my Jandy valve pointing toward the pool would seal off any flow to the spa. I built a small deck over it and turned it into a place to sit. This effectively hid what I thought was a bone dry cavern. After pulling some of the decking away recently, I realized the spa was full (gross and full). Careful testing revealed that one of the return jets was leaking into the spa. The leak stopped when the pool level was equivalent with the spa level. I suppose this is a physics lesson.

One question is: how is water getting to the spa returns when my automatic Jandy is only turned toward the pool? Apparently the Jandy valve is not fool-proof (this is my theory) and water is getting past the valve and to my spa. Does this sound like a good theory?

The bigger question is, how would you recommend I solve this leak down to the spa that I'd prefer to remain dry. I am never going to use the spa, so not afraid to make permanent decisions. I feel like I have three choices:

1. Cap each of the spa jets with those 1.5" winterizing, threaded caps and hope that stops all water intruding into the spa
2. Cut the plumbing to the spa at the pump house and cap off pressure side flow to the spa entirely
3. Take apart the Jandy valve and see if I can repair it

I would very much like to hear opinions on that.

Regarding (suspected) Leak #2:

I don't have a positive dye test to confirm this, but I suspect my skimmer has been leaking for some time. Visual inspection reveals several places where the tile and mortar have worn away and it looks like water can get between the wall of the pool and the skimmer. The concrete near my skimmer looks to be "raised up" a fraction from last year. It rarely rains where I live (Nor Cali) but this piece of concrete definitely looks like it's come up of its own accord. No tree roots or other explanations.

So I purchased some that 2-part epoxy patch goop and patched up anything that looked like a suspect. I suppose I don't have any direct questions here, but would love to hear any thoughts on likelihood of 30 year old skimmer leaks.

I hope my questions were obvious in here. It's been a strange and educational 7 days. I'd very much like to get back to water loss equivalent with evaporation. Thanks for reading my tale of woe.

Tommy D

 

[newdude]

I hope my questions were obvious in here

You did well explaining it.

Pics of the equipment and spa will seal the deal.