I almost had to dive in a pool covered by a sheet of ice today because we thought the main drain may be leaking. Luckily, the machine we use to see if it is actually leaking told me that it was holding at the moment... water is just below the light, so I am hoping it is either there or just in the main drain line where it reaches that level on its way to the pump. Needless to say, I am not looking forward to that kind of dive anytime soon, even with my dry suit and the extra $80/hr I get for diving. I hate the cold.