I closed my pool today. In doing so, I blew the main drain line out using a compressor. This usually causes the main drain cover to come off because it is not physically fastened down.
When I looked into the main drain, I saw a piece of plastic pipe sticking into the main drain cavity from where the main drain connects to the pipe under the pool floor.
I swam in to take a look. I could not remove the plastic pipe but it did slide back easily into the main drain pipe. The pipe was very thin and I could squeeze it with my fingers. Also, the piece of pipe that was visible had perforations in it.
I'm thinking that the piece of pipe is not part of the actual plumbing because it was so thin. Also the spot where the main drain connects to the drain pipe appeared to be in tact.
What was it?