Yeah, you know where this is going. Initially I had a hole drilled in my return line so it would suck air and kill the siphon during a power outage so I wouldn’t siphon all the way down to the outlet of the return fixture.
Well, over time, that little hole got smaller and smaller as various “deposits” started to fill the gap. Needless to say, I had about 7gallons overflow on me. It was sucking air, but not enough to stop the siphon. Power was out for who knows how long, but long enough.
Atleast my setup is in the basement, on a vinyl flooring, and I have a nice wet vac. Suck it up, turn the fans on, and whip out the swiffer. 
And…that siphon hole just got a little bit bigger and will get MORE attention.
Keep it in the tank!
-Rob