Concrete pool sprung a leak. Now what?

[Monomial]

So I was duped and had my pool constructed by a cowboy. I realize it now, but I can't change the fact that I was foolish and got cheated. In all honesty, it worked for about 2 months after a rough start, and I was actually excited to be able to use it. It is an overflow design with a few quirks created by the fact the guy didn't know what he was doing.

Now however, it has developed a serious problem. 2 days ago I noticed a crack on the sand wash deck of the pool. Since then, I have also noticed the water level dropping about 4cm per day. This is substantially more than evaporation could account for, and because it started at the same time as the crack formed, I am assuming it is due to a movement of the structure...probably a cracked pipe of some kind.

The question now is what to do. I am currently running the test where I shut off the pump overnight and see how far it drops. Tomorrow I will refill the pool and turn the pump on and see how far it drops. From what I have read that should tell me if the leak is on the pressure side or the vaccum side of the lines, or if the levels are equal then it could be unrelated to the piping at all.

The next test I have seen recommended is to use a dye. The only dye I can easily get is the red pH die from a test kit. I would guess that is OK, but can anyone explain exactly how to use it? I don't think dropping it on the surface will be useful. I have read to use a small squirt bottle under water. Can anyone recommend an appropriate bottle? Also, I doubt I can hold my breath long enough at the deep end of the pool to get any useful data. And coming up for air will likely disturb the water to the point any test is useless. How do the more experienced people deal with this issue? Do I need to get scuba gear? (I am not certified.)

The next thing I hear is about pressure testing the pipes. Some people seem to claim this is possible without draining the pool. Is this true? It isn't even clear to me how you can pressure test the pipes on a pool, as there doesn't seem to be any way to close the ports.

I have also read to try plugging the drains and water returns with rubber stoppers. Exactly what are those and how do they work?

There is also a product called "Fix-A-Leak" I have seen on the internet. Does anyone know if there is a Thai source for this or a similar product?

Does anyone have any advice for me? How would you begin with this problem?

Thank you for any advice.

[IMHO]

The first step is as you mentioned:

Turn off all pumps and check how much the water level drops overnight. Without sunlight evaporation will be absolutely minimal, and without pumps running, a bad pipe connection isn't going to leak a significant amount of water.

[BEVUP]

You were not duped most are cowboys just look around. But certainly feel sorry for you as finding a leak amongst a concrete jungle is very difficult.

I guess the rubber plugs are to block the out let holes to let the pressure to build up & hopefully the pump will stay off thus eliminating that side of the problem

If the pool its self & at that rate you may see dirty water

This would be out of the question but back home they would inject gas into the system to detect were the leak is

Am building a above ground concrete pool at the moment & from what i am seeing another problem you may face in the future would be concrete cancer as they no idea of this - told them reo should be in the middle not touching sides - (guess what they are doing) putting reo from shutter to shutter to keep in the middle & still not worrying about the bits that still actually are

I guess there solution is no worry render will fix all

& my further guaranty will be to use the Webber products

[Chaichara]

You were not duped most are cowboys just look around.

I think this is a rather unfair comment. If would be akin to someone saying that most farangs living in Thailand are criminals hiding from justice in their own country. Well, indeed some certainly are and indeed there are a lot of so called pool constructors who produce absolute rubbish. Ask to see pools they have built and talk to the customers before deciding.

The answer is caveat emptor.

[derekwyoung]

Hi ,my name is derek , I built my own swimming pool at a property I owned about 10 years ago and it worked fine until there was a powerful earthquake in myanmar a hundred or so miles away ,I felt the ground move it felt like a couple of inches back and forth , any way after that my pool started to lose water, so turned off the pump and left it to see how far it would fall, when it got to the return water outlets it stopped falling indicating the leak was on the return water side. The return water outlets were about 10 inches below the normal surface level so with much reluctance i dug up that end of the pool and replaced the blue plastic water pipes with black hi density polythene pipes that I got from an agricultural center ,put it all back and filled and turned on ,seamed to work fairly well except when I was using the cleaning hose connected to the skimmer ,the pump kept getting air in it and would stop cleaning, clearing the air from the pump would start it working again and it would work for about 5 min and then start cavitating again (air in pump makes noise as it is compressed). Found a crack at the bottom of the skimmer so dug that up and replaced it and all was ok , I would recommend that any one thinking about building a pool should use the hi density polythene pipe between pump and pool ,it is very tough and can bend a bit. Allowing the water to fall until it stops wil give u the height of the leak, when u reach that point add 2 inches of water gently add dye clost to the wall .The dye will disappear into the leak leaving clear water next to the leak, hope that this can help u

[Monomial]

So the results of my initial tests are in.

I ran the tests during a 10 hour period from 8 o'clock in the evening until 6 am the following morning.

The first night I left the pump off completely. There was no perceptible change in the water level the following morning.

The next night I did exactly the same thing, except I turned the pump on. By 6 am there water level was down somewhere between 4mm and 7mm. The uncertainty is due to a slight breeze at night that was causing ripples on the surface and made it difficult to establish an exact starting point.

So based on these calculations, when the pump is running I lose somewhere between 24 and 39 liters per hour.

I dug up the water return line as far as I could until I reached the edge of the concrete deck which surrounds the pool. There was no perceptible unusual wetness to the soil anywhere along the line, which indicates that the leak must be underneath the pool. The return line runs directly down the center and underneath the floor of the pool, with 4 return ports evenly spaced in the floor along the 12 meter length.

So the big question now is what should I do? Is there anyway to repair this without completely destroying the pool?

Any thoughts or ideas? Any recommendations on who I should call? Or should I simply ignore it for now, and just plan on adding salt and acid periodically to maintain the environment? My water quality is pretty bad with alot of ferric oxide, so I have found I need to run the pump and filter about 8 to 10 hours a day to keep the water clear. The leak isn't so bad right now that I couldn't just live with it, but my fear is it will get worse with time.

Thanks for any advice.

[IMHO]

OK well, that's a much better outcome than a leak on the pool structure. How hard it is to fix depends on how hard it is to excavate and expose the pipes I guess.

The next tests should probably be to work out whether the leak is on the inlet side, or the return, if possible.

Is it possible via valves to direct your pump inlet side between the balance tank and the main drain? If so, spend a night pulling water from only one of each:

1. if you only lose water when pulling from one of them, and not the other you know which circuit your problem is coming from.

2. If you lose water no matter which one you use, the leak is likely on the return side.

[Monomial]

IMHO, I'm not sure I understand your statement "That is a much better outcome".

Let me explain. Based on my understanding, the leak has to be on the return side.

If it were on the inlet/vaccuum side, then the test results should have been reversed for the following reason:

Without the pump, the pressure on the inlet side is equal to the water pressure from the pool. With the pump, the pressure is equal to the water pressure from the pool minus the vaccuum from the pump, thus turning on the pump lowers the pressure on the inlet side, thus reducing any water flow from a leak.

Similarly, on the other side of the pump impeller (the return side), with the pump off there is only back pressure from the water in the pool on the return pipe. That doesn't seem to cause significant leaking. Once the pump is turned on however, the water pressure increases and the water begins to leak out.

So I am looking at a leak in the pipe somewhere directly underneath my pool floor, because it is completely dry all the way until it goes under the pool. I guess I don't see this as an excavation project. More like an entire pool replacement. It means jack hammering through ceramic tile and concrete along the entire length of my pool floor until I can expose the pipe in the sand below. Then fixing it, and then finding someway to repour the concrete and reseal the entire bottom of the pool.

This sounds like an incredibly expensive repair, if it is even possible without rebuilding the entire pool. A simple crack in the concrete structure seems trivial by comparison. This seems like absolutely the worst outcome possible to me.

Am I not seeing something here? Is there a way to correct this problem without breaking through the floor?

[IMHO]

Sorry, I was envisaging a pool where no pipes run under it at all - i.e. even the main drain(s) are located at the base of a wall, so still somewhat serviceable.

If the leak is in a pipe that's under the pool, wow.