Define silent. Actually, I don't really know, because I ran it along with a huge Iwaki - yes, there was noise, although I don't know how to quantify it. Could I sleep through it? Sure. Could I tell if the power went out and the house fell completely silent? Yep. (Don't know if it was the pumps, the lack of splashing water or just that reefer 6th sense.)
And yes, the output is 1"