What type of pipe for bottom drain

"Hal" wrote in message
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There are lots of different configurations being used. I know one
guy who cut a hole through the liner 1" smaller than the drain and
shoved the drain pipe through about an inch. The liner forms a seal
right around the pipe. (He didn't use a clamp, said he didn't need
one.
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I did exactly this. I used the very method you are describing. No clamp, so
far no leak after almost 2 years. I think I have a link to it under
http://www.iheartmypond.com/Design/DIY/Fittings/.

BV.