We just bought a new house with an inground pool---I've had some friends come by and show me the basics, and I'm perusing the pool school stuff, but no one has been able to tell me much about this...This picture is of an item on the deeper end of the pool---I originally thought it was a broken light, but I now know that we have fiber optic lights, so that's not it. Someone mentioned it might be part of an older salt system, but I haven't been able to confirm...anyone here know what this is?