Main drain weird major leak..please help...

[Coops]

Hi Everyone. I have a major leak problem and it's pretty weird. Tried everything we can think of. Basically, pool will be fine for months, then usually after cleaning or after a landscape worker has been there, it starts leaking majorly. I mention the landscaper because my wife thinks he may be doing something to cause it on purpose. He used to take care of the pool too. The level drops a foot every day. It will leak all the way to the bottom. We keep filling and out of no where sometimes days or weeks later it holds water again for weeks or months. Never know. Any ideas would be appreciated. We have already tried detaching all pumps and still it loses water. Tried so many things that I can't remember. If there was a crack or something I'd expect it to leak all the time and not stop.
So what I know, concrete pool with tiles. There is no hydrostatic valve.

Thanks for any help!!!!

[Denniswiseman]

What is this an inground or above ground also what is the construction
The only thing that comes to mind if this is an inground pool would be a faulty hydrostatic relief valve in the main drain. Designed to allow ground water to leak into the pool when empty to prevent floating

[Coops]

Sorry, forgot. Yes inground pool. Cement with tile.

[Denniswiseman]

The hydrostatic relief valve could be your problem then
When it empties again investigate and replace
The only other alternative is to block the main drain either temporary or permanent

[Teapot]

Hi Coops and welcome, you haven't given us much info on your pool yet so always a bit tricky to try and guess. I agree with Dennis, the first port of call would be your main drain and hydrostatic valve if you have that option fitted? Another possibility is your worker is doing something that starts a siphon action, maybe out of the multiport to waste line, again if your system has that?

I would, make sure on the next visit you monitor exactly what your person does, make notes and report back, they maybe doing something without realising it, have you reported this issue to them?

[Coops]

Hey, yes they know the issue but it's been a year and still not fixed. If the landscaper is sabotaging it, thry won't tell me anything:(
I'm told there is no hydrostatic relief valve.
It must have something to do with the main drain since it takes about a week for the pool to drain all the way down to the drain. But I would have figured the pool would be leaking all the time and never hold water but like I said, it does hold water sometimes.

[Denniswiseman]

Who told you their is no hydrostatic relief valve. Some experts aren't expert
Can you not temporary block the main drain to see if it's related
A lot of people have done away with problematic main drains

[Teapot]

Seconded Dennis, especially as main drains don't actually do very much. Dirt enters from the surface of the water so skimming is the best action.
Having any main drain suction reduces the skimmer action.
Do as Dennis suggests and buy a bung and fit into the main drain.
That would stop water loss if it was a main drain or siphon issue. The water then would only drop to the level of the skimmer.
If your pool person/gardener has solved it in a year get rid of them from pool duty they are useless.

[Sampool]

Hi Dennis

Just seen this thread one of the easiest ways to find out where the leak is coming from is to pressure test all your pool fittings,
It could be a faulty hydrostatic valve, which yes you could bung it off but I wouldn’t recommend it specially if your in a high water table area. Also your multi port could be giving way as these do tend to happen over a certain amount of time. Do you have a ball valve on the wasteline that you open and close to do backwashing and rinsing? If so make sure this is shut that would prevent the water(if it’s letting by) going down the drain.
I also wouldn’t recommend bunging off the sump completely as this is there for filtration purposes, if your pool ever goes green it will take you much longer and harder to clear it just using the skimmer alone.

Any questions feel free to ask, I am a pool engineer and installer with 12 years experience. Happy to help out.

[Denniswiseman]

Hi Sampool
Thanks for your input but a few things that you may not have noticed
The water drains completely from the pool so there is very little chance of floating
The fact that it isn't constant would negate some of the other options
Bunging the return was seen as a temporary option to determine whether the main drain was faulty, also to pressure test the pipework you would need to bung up the pipes
A main drain isn't necessary and in some cases dangerous causing entrapment (this is why some have two main drains linked so that the suction is halved)

[Teapot]

I also wouldn’t recommend bunging off the sump completely as this is there for filtration purposes, if your pool ever goes green it will take you much longer and harder to clear it just using the skimmer alone.

The main drain does practically zero for water filtration. They circulate clean water most of the time unless you actually push dirt into them. Plenty of my customers do not have a main drain at all with no issues, should they have an algae problem it is just as easily cleared up with correct use of chems and just a skimmer.
I have 17 years experience as a pro.

[Coops]

What is this an inground or above ground also what is the construction
The only thing that comes to mind if this is an inground pool would be a faulty hydrostatic relief valve in the main drain. Designed to allow ground water to leak into the pool when empty to prevent floating

Hi Dennis thanks for the info. Ok, I'm going to send the pool caretaker some questions. Can you give me some questions for construction, pumps, anything that may help the forum figure out the problem? Thanks again!

[Coops]

I was thinking if just blocking off the main drain but would still prefer to find the problem.
What questions would all of you ask my pool guy to get more info for the forum to help figure out the issue? I'll send him an email tonight.
Thanjs again.

[Teapot]

Dennis suggested temporarily blocking off the main drain (quite rightly IMO) to see if this stops the problem thus you can then concentrate on that area. Buying a plug is cheap compared to other methods.
Oh questions for your pool guy,
Why are you working on pools when you clearly don't know what you are doing!

If you could post some photos of the equipment pad it may help us

[Denniswiseman]

Once you sort this main drain problem, get yourself a decent FAS/DPD test kit and maintain your pool yourself. Strips and Pool Stores are unreliable
If you are in the States a Taylor K2006c or TFTestkits TF100. I purchased the Taylor with international shipping