Priming hook for closed loop intake. The threaded cap at the top unscrews and allows water to be poured into the pump to get it primed for starting. Also shows Loc-Line Y return.
This also shows how I colored the PVC inside the tank black. I saw a thread on RC where Randy Holmes Farley said a Black Sharpie magic marker would not harm a reef tank.....so rather than spend $40 something on a gallon of reef safe epoxy from Aquatic Ecosystems, I just uh...colored it in. If you look closely at it in person, you can see variations in the color, (darker and lighter etc) but when the back of the tank is painted it will be much less distracting than the white PVC would have been.
Nick