I'll jump quick jump into this.
Quick explanation of a closed and open loop is:
Open Loop is like your overflow and return pump. In otherwords there is a gap or "open" space between the where you take the water out of the tank and put the water back in.
Closed loop is where you have the PVC
pipe attached to the input and output of the pump and there is no gaps in where you take the water out of the tank and put the water back in.
Typically the pump on the closed loop is put on the floor or a shelve and the pipes are run there.
As for the Mag7 noise I siliconed an old PH back to mine and put suction cups on it. Like was mentioned above you can rubberband airline tubing on the bottom of it or many places sell rubber pads you can set it on.