Concrete pond with a leak!

  • We are currently upgrading MFK. thanks! -neo
If you don't want to drain it,
The pool guys go in on SCUBA with a big syringe or turkey baster full of food-dye. They squirt the dye near to a potential leak point or crack and you can see the dye get sucked in. From there use two-part putty epoxy and gloob it into the hole with your thumbs.
 
MonsterFishKeepers.com