Place the powerhead side in the water where you want it and hold it there. Then take the other half and place it on the otherside of the glass away from where you have your power head held. Then slide that piece up to your powerhead. This should stop from them slamming together.hey i just got my powerhead delived. and after looking at the magnets. i am realy scared to use them as there so strong. how do u attach them without breaking the glass