How far to let leak drain?

[Poconos]

Thanks for the comment about the patch jig. Hope I never need it again. I think the rule is no less than 6" at the shallow end but that is only a general guideline. Personally I wouldn't let it get lower than it already is. I believe what will happen if you drain really low is the liner will stretch and start to tear where it is attached at the coping. Since you have a main drain I assume you have as deep end. Making accurate loss rate measurements can tell you a lot. As the depth of the water above the leak decreases the leak rate should decrease. If it doesn't then you have a deep end leak as was my case. I looked at this thread from March this year and I don't have anything else to add at this time.
http://www.poolforum.com/pf2/showthread.php?t=101
Good Luck.
Al