Pool leak follow up - fix a leak for main drain?

[jcverheijen]

I wrote about this 1.5 seasons ago (Pool leak mystery: help me create a plan of action please....), finally have a new update....

Background: had pool replastered. Before doing so, PB did pressure test of all plumbing lines, which cleared. When we bought the house, main drain was plugged, pipe was capped at equipment pad. Asked PB if main drain could be repaired. He supposedly tested and gave us good news: there was no leak in main drain. Asked PB why it would have been capped and he said that people do strange things sometimes. Should have known better then.....

Any way, pool was replastered, main drain reconnected and we had a leak afterward. Leak stopped right around skimmer level. PB did dye tests around main drain, light niches and skimmers and all were cleared. PB said he could do no further testing. Tried to figure it out myself but hit a dead end. Finally hired American Leak Detection who confirmed no leak in my skimmer lines. They did a hydrostatic lock test on main drain, and it lost pressure quickly. ALD says main drain has leak, probably at height of skimmers. ALD said that if leak was on top of main drain rise, far from main drain intake, dye test would not have revealed this. So this seems to be consistent with observations.

Torn about next steps. I can plug main drain and see if leak stops just to confirm. If it does, I need to decide whether to fix main drain. If confirmed that main drain is the source of the leak, I plan to dig down around where the main drain surface and enters the pump. If leak is at first elbow, it will be an easy repair. If not, I will leave it plugged.

One other option that is intriguing: I read about "fix a leak" which seems to have a reasonable chance of success for pressure side leaks. Does anybody have experience using this for suction side leaks? Can one reverse the plumbing at the pump to fix a main drain leak? How would you do that, and how would you ensure the fix a leak (which is heavy and sinks to the bottom) continues to be circulated through reversed plumbing? What's the risk of reversing flow, any damage to chlorinator, heater, etc? I would plan on putting filter on bypass.

Thanks!

 

[mas985]

The biggest question is why do you want to bother fixing it? These days we recommend that new pools just skip the MD for the very reason you are experiencing. They are just too prone to leaking. Also, they are not required for proper pool maintenance and are more of a liability than an asset. I would just abandon the MD and fill in the area with concrete and plaster.

 

[jcverheijen]

The biggest question is why do you want to bother fixing it?

Mainly because it makes draining the water below the returns easy when I close the pool for the winter. Otherwise I have to buy a submersible pump, 2" hose, etc.

I would just abandon the MD and fill in the area with concrete and plaster.

Yes, that would have been an option when I had the whole pool replastered. Unfortunately my clueless PB told me the MD had no leak, so that opportunity is now gone. At this time, if I get rid of the MD, I would just plug it. Don't want to spend a few thousand $ on draining/refilling the pool just to get rid of the MD. Filling / plastering could happen next time that the pool is refurbished.

 

[markayash]

My pool is doing similar things but seems if I close the main drain valve it helps I don’t know if the suction shifts things around but my lines are under the deck so expensive to repair

 

[mas985]

Mainly because it makes draining the water below the returns easy when I close the pool for the winter. Otherwise I have to buy a submersible pump, 2" hose, etc.

A vacuum hose connected to the skimmer line can do a drain down just as well.

 

[jcverheijen]

My pool is doing similar things but seems if I close the main drain valve it helps I don’t know if the suction shifts things around but my lines are under the deck so expensive to repair

In my case, closing the main drain valve made no difference. But I think that is consistent with the leak being in the riser of the main drain plumbing. Water goes out the leak, gets replenished from the pool through MD. Whether valve is open or closed does not change pressure in the pipe.

 

[jcverheijen]

A vacuum hose connected to the skimmer line can do a drain down just as well.

Thanks mas985. I have tried that in the past. Worked well until we got to just about skimmer intake level. Once there is no more water above the plate that connects vacuum to skimmer, it lost its seal and just sucked air.

The plate on my vacuum hose covers the entire skimmer filter basket opening. Are there other ways to connect vacuum hose to skimmer, like screw it in the hole where you would screw in the gizzmo for winterizing? Or would a brand new plate maintain a seal even when there is no more water on top of it?

If I can use skimmers to drop water level for winterizing, I agree that plugging main drain is a no brainer. My brother in law has scuba gear, would make for a fun project once pool is open and COVID-19 lockdown is over. That being said, if there is an easy way to fix the main drain, like with "fix a leak", I would still be interested to hear about it.

 

[markayash]

How would you close a main drain? Are there covers that replace the opening?

 

[jcverheijen]

How would you close a main drain? Are there covers that replace the opening?

My plan was to unscrew the grate/cover and plug the drain line with a rubber winterizing expansion plug, unless there is another way to plug the main drain short of draining the pool completely and filling with gunite/plaster?

 

[mas985]

Thanks mas985. I have tried that in the past. Worked well until we got to just about skimmer intake level. Once there is no more water above the plate that connects vacuum to skimmer, it lost its seal and just sucked air.

The plate on my vacuum hose covers the entire skimmer filter basket opening. Are there other ways to connect vacuum hose to skimmer, like screw it in the hole where you would screw in the gizzmo for winterizing? Or would a brand new plate maintain a seal even when there is no more water on top of it?

You can run a low flowing hose over the top of the skimmer plate so it maintains a seal. Just enough to keep it under water but not overflow back out the skimmer mouth. It shouldn't take much extra water to do this.

 

[jcverheijen]

You can run a low flowing hose over the top of the skimmer plate so it maintains a seal. Just enough to keep it under water but not overflow back out the skimmer mouth. It shouldn't take much extra water to do this.

Thanks mas985. That's how we did it in the past. I think I was probably using a bit more water flow than needed

 

[markayash]

My plan was to unscrew the grate/cover and plug the drain line with a rubber winterizing expansion plug, unless there is another way to plug the main drain short of draining the pool completely and filling with gunite/plaster?

Have a friend who like to scuba? Might be cheaper to give him $50

I am not 100% sure where mine is, not trying to be nosey but roughly how much did they charge you to come check it? I am debating having them confirm where mine is

 

[mas985]

Do you have a single speed pump, two speed pump or VS? Running on lower speeds can be beneficial since it reduces the suction at the skimmer. Alternatively, for single speed pumps, you can throttle the return side to lower the suction some.

 

[BNighGrow]

You can use this adapter to run the vacuum hose directly to the skimmer suction port. I've had my main drain plugged for over 4 years without issue and my only advice would be to replace/swap the expansion plug each year. They seem to lose their seal overtime especially through winter. I have zero experience with using Fix-a-leak as it is designed to be used on the pressure side. Speaking from experience I'd cut your losses and plug the main drain.