Electronic timer - normally on, timed off
Back when I was doing salt water (6 -125 gallon tanks at one point) I had some "black box" timers I picked up at the swap meet that were set to be normally on but when triggered had a timed off period that lasted from 1 to 15 minutes, depending on the setting. They worked really well to do a temporary shutdown on the filters when I fed the fish and I'd like to add that to my current tank. Unfortunately, my mind is going and I can't remember what they were called officially.
Does that ring a bell with anyone?