Main Drain Leak?

[joesc230]

Hi all,

I had a fence installed around my pool while the pool was closed. During the install they hit the main drain when digging out for one of the posts. We drained the pool down and had the punctured area replaced. We thought we were good to go, but ever since opening the pool we've noticed a lot of sputtering from the returns and a good amount of air visible via the filter pump sight glass. We had the PB come today and he said he's sure it's because caused by another main drain leak. He said that the fence installer probably punctured another area of the main drain, but didn't realize as it was probably a small puncture because we aren't losing water. He said that he is certain it's a main drain leak because he tested it out and all of the valves are fine and when he changed the setting on the main drain valve to only rely on the main drain, the air in the system suddenly got even worse and then when returning the valve to the regular position the air viewable in the sight glass returned to previous state (still air viewable, but not nearly as bad).

Is his logic making sense? Hopefully I'm explaining it clearly...let me know if you need more details.

He actually is recommending I don't do anything because my water level isn't dropping. He sort of said to leave well enough alone, but I don't think I want to risk the problem getting worse over time and turning into an issue (i.e. causing damage under our paver patio, eventually leading to bigger problems). I also don't like how much bubbling and sputtering is coming out of the pool returns...looks concerning to me. Here's a link to a video so you can see what I mean: https://youtu.be/cwUiZ1gVstg

Thanks for any advice on this! I really just want to make sure he's not making an assumption that I'll end up paying a lot for and still have no fix. He wants $500 just to find the leak and then said it would cost around $500 more to fix the leak.

 

[Richard320]

He's making sense. Confirm it yourself by shutting the main drain off completely at the valve. If the bubbles go away, it's somewhere in the main drain line.

I would call the fence installer and let him know you expect him to pay.

I suspect the PB price might get more reasonable if you ask him to check it in October, when he isn't busy.

 

[Jimrahbe]

Joe,

I see two options..

Option 1... shut off the valve that controls the Main Drain at the equipment pad. This won't fix the hole in the Main Drain pipe, but it should stop the bubbles. I am assuming that the hole is above the water line, so you will not be leaking any water. If turning the valve off at the pad does not stop the bubbles, then repairing the main drain line will not stop the bubble either. Pools do not need main drains to function normally.

Option 2. If turning the Main Drain off at the equipment pad stops the bubbles then what your pool builder says makes sense. If cost is not an issue, then it would make sense to repair the pipe.


Thanks,

Jim R.

 

[joesc230]

Thanks to you both for the input.

I tested it out and shut off the main line and it actually looks like the leak gets worse when doing so. Here's a link to a video where you can see how the filter looks with the main drain off. Then, I changed it over to the normal valve setting and it gets better (less air, but still not good). Then I switch the valve over to only rely on the main drain and it gets much worse (as expected). At the end of the video you'll see that I return it to the normal position and it gets a little better. Does any of this help further determine the problem?

Video: https://youtu.be/UAU7fj2yr1c

When I checked the system out this morning (it turned off last night from automation, and turned back on this morning from automation), I realized that it was running dry for about an hour, so it wasn't able to self prime. Of course, I shut it right off once I realized. When I opened the filter pump, the water inside was very hot and a little steamy. I let it cool off and ended up getting the pump to work again by dumping some water into the filter to remove air. I'm going to keep the system off automation until I solve this problem.

 

[Richard320]

Since the problem doesn't disappear with the main drain closed off all the way, it's probably not there. And if you aren't losing water, the leak is above the pool water level.

I would start by coating the 3way valve stem area with shaving cream. Reasoning: it's shared with all the lines that leak, but the leak worsens in one position. Could just be a flat spot on the stem or a deformed O-ring. What you'll see, hopefully, is foam being sucked in- a crater in the foam - and possibly foam in the pump basket or shooting out the returns.

Then move on to each individual pipe connection between the 3way valve and the pump inlet. And also the pump drain plug and the pump basket seal. When you restrict the flow by drawing only through the main, it might be enough to cause it to start sucking air, and harder than it does normally.

 

[joesc230]

So I did further testing and figured out that the leak was a result of the o-rings in the 3way being in bad shape. Very simple fix once figured out! That goodness I didn't have the PB come back and charge me $500 to do a pressure test.

Thanks for all your advice!