Diagnosing a plugged main drain line

[djkoell]

We've owned our home with pool for several years and just drained the water due to high CYA. While the water was out I took a look at the main drain since we've always had an issue with debris not clearing out of the pool. I took the main drain cover off and found a plug in the main drain. Based on some other posts, I understand I may have a leak. Would appreciate any guidance on how to best troubleshoot the main drain.

I took the plug out and put a hose with a ballon-type "clog buster on a hose and put it in the main drain. I was hoping to see water come out into my pool pump, but saw water bubbling up from the ground about 5 feet from the pump. I dug up the pipes and discovered the main drain pipe was cut and not even plumbed into the system! The pool as only been working from the 2 skimmers and 2 wall drains.

Here's a video of the pool and main drain issue:
6/2018 Pool Drain Issue - YouTube

So my question to the forum: What's best way to troubleshoot and potentially address issues?

- I bought plugs for the drains and one plug with an air valve allowing me to pressurize the disconnected main drain pipe. Will pressurize with 15psi and see if ti holds. If it holds I should be able to tee the main drain line in with the other two wall drains.
- I bought dye in a syringe and will check if there is any leak once I remove the plug from the main drain. I noticed there is a bunch of what looks like concrete in the main drain box. I'm wondering if this is the result of a prior repair.

Anything else I should consider? Really appreciate this community and welcome any advice!

-Dan

 

[Richard320]

You're doing what I would be doing. I have no idea if we're correct.

 

[jimmythegreek]

you are actually fine working off 2 skimmers and 2 wall drains. U mean 2 wall returns or do you mean drains like suction? I dont have main drains in my pool and many others dont as well. If you rly wanna get it going you are on the right track. Just plug the main drain and put a cap w a threaded port on pipe and pressurize and see what happens. Id bet it was cut because its bad under pool or in a bad spot to repair and they gave up on replacing that line.

 

[blakeusa]

If you found where the drain line is damaged - pressure test the line to see if its OK.

Put the plug back on your main drain.

Rig up a test cap where the pipe was leaking with a pressure gauge and inlet - which would allow you pump pressured air with a compressor at about 15psi into the line. Let the line sit for a few hours or a day and see if it holds pressure. If it does then repair the broken pipe and your good to go. If not then you have other cracks or leaks in the pipe. Cap it and forget it.

You could also hire a leak detection company that will pressure test the line for you.

Or you could just leave it as is and not have a main drain.

 

[Pool_Medic]

You mention in your video “ so we don’t get this junk in the bottom of the pool anymore”

Fixing the main drain, regardless of costs will not stop that. The main drain will not act like a skimmer for the bottom of the pool.

IMO. Leave it plugged.