if you re thinking of using k1 for the middle chamber then look at the drawing that i made. that's is exactly how i made mine.
After the socks, the water will goes up then over the ledge and drops down (no noise if you do it right with the rigth height) and hits the k1 and turns them. you could add an air stone for more air and place it where the media does not turn or not cause my sump is a little shorter but wider and taller.