I got a call from the wife asking me what I had done to the pool this time! I have a history of draining pools by forgetting to shut things off, draining fishtanks on livingroom floors, etc. She went on to say that my water level had dropped about 6" and was below the skimmer. In my calmest panicy voice I had her go over to the pump and turn it off. Once she got there she noticed water spraying from a PVC compression fitting. I went home and loosened and reconnected the fitting. It seems that the increased pressure in the sand filter from adding DE and CYA increaser had pushed the improperly installed connection to the leaking point. Good thing she was there to prevent a drained pool or/and a burned up pump. Be sure to check fittings!