This was 11 years ago on a large LFS system. During the night, something caused the sump (6 feet deep, 4 feet wide) to get low on water. The pump (I think it was a 2 hp pump) started sucking air and water. All of the larger fish on the system died, many of the smaller ones made it. You could see the gas bubbles in the fins of the larger fish. It was a very sad day...
