Yeah definately if the pump is running the form of filtration then definately a no no to turn it off, and yeah I myself have had the same thing happen a while back ryan on a grow out tank... I didn't have my spray bar running however, but I had the out take sitting so it hit the water surface, so it broke the surface, but it slipped off what I had it on and it went beneath and I came home to pretty unhappy chappies, naughty naughty, visually kicked my own butt for that one..