Leaky drain line

[Gene]

When I turn the brass insert that sits inside the skimmer, so that water is being sucked from the drain, (rather than the skimmer box),i get air bubbles in the dishcharge lines. It seems as though the pipe has an air leak (hole), somewhere between the drain at the bottom of the pool,and the skimmer box. When I bought this house with the pool I had acid washed the plaster. I did not realize I needed to dilute the acid. I'm thinking I may have weakened the copper pipe under the pool with the acid, and now, 10 years later,the pipe has worn through. My question is this. Is there anyone who makes something like a "liner" that can be inserted down through the skimmer opening? Im thinking maybe some thin wall PVC or something similar? Any ideas or help is very much appreciated.
Gene

[ChuckGeo]

Could be a leak in the main drain line, or in the suction line from the skimmer back to the pump, the only way to know is to pressure test the line from the main drain to the filter pad. Unmfortunately, I know of no way to sleeve the inside if the pipe. The repair usually involves digging up the problem and repairing it.
Another solution would be to not operate the main drain, your pool should operate just fine on the skimmer only. As long as you're not loosing water you should have no problems running just the skimmer, in fact, many pools are built without a main drain! You can try opening the main drain partially and try to find a setting that doesn't draw air.
By the way, if this line has a leak in it, and your loosing water, the loss will be greater when the pump is off (no suction on the line) than when the pump is on.
Let me know how it goes.

[Gene]

Thank you Chuck. Yes it does lose a slight amount of water. I did test the drain once with standing water with the floor drain plugged, and it didn't seem to leak at the time. It may have been leaking however because I only let it sit for a few minutes, but I did not see the level drop at the skimmer pipe. My guess is that under suction, the small leak is more apparent,and thus the air bubbles. I'm going to isolate the leaky pipe by plugging the drain at the bottom of the pool, and also at the end of the pipe just below where the pump suction line tee's into the drain. This should allow me to use the skimmer, and also connect the vacuum hose when needed. The vacuum hose doesn't work well at all right now because of the leak. The pools way too old to dig up the plaster I think. The deck,coping,and tile is in just fair condition although the pool is certainly nice in the summer with air temps sometimes 110 degrees or more. Thanks so much for your advice chuck,...Gene