Main drain clogged - did I break it more?


Well-known member
May 29, 2017
Worcester, MA
My main drain is connected to a second port at the bottom of our skimmer basket. We just bought the house this year and have never had the pool. I'm determined to get it working properly.

Over the past two weeks I've added a Weir door to the skimmer, which now works great. I also realized I now need one of the float valve assemblies to set at the bottom of the skimmer to help divert some water from the main drain to the filter as well as act as a safety should my water level drop below the skimmer.

Anyway...I discovered this week that my main drain is plugged. I stuck a hose down the port in the skimmer basket a few days ago and dirt and debris erupted from the main drain at the bottom of the pool. When I try to connect to the port in the skimmer basket with the vacuum hose there is A LOT of bubbles and cavitation. I think this is likely because the line is clogged.

I read some posts on here which suggested using a "Drain King" which I purchased today and used. I then suctioned the drain line again using the vacuum tube.

I then checked the skimmer basket on the pump and there was large chucks of what looked like plaster in the basket.

Did I do damage with the drain king and break off some plaster? Or is it more likely that this plaster somehow broke off years ago, and got lodged in the main drain which I have now just broken free? It is a 38 year old Gunite pool and I believe it was refinished a few years back. I hope the debris is from this refinishing.

After using Drain King my line is still partially obstructed. Any other ideas on how to clear this blockage? Is there a risk the Drain King will burst the drain pipe or plaster? I'm petrified of leaks.


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
It's very likely that plaster has been down in the drain since the pool was refinished.

The drain king won't build any more pressure than what is in your household system. Figure if the garden hose can withstand it, your pipes should be able to as well.

The bubbles are most likely because of the vacuum hose. Unless it is sealed to the suction port, I;m sure some air is being drawn down in there, too. If you don't see bubbles on normal operation, don't worry.

You could try making multiple dives to the bottom to unscrew the drain cover and see what you can vacuum out of the well down there. I'm not sure it's worth it, though. I will tell you this: even if things are perfectly clear, you won't feel a lot of suction at the main drain. The cover is designed to prevent that, so nobody gets trapped on the floor. You can brush a leaf towards the drain and it will slide right past it 1/4" away.