This could go on my last thread but I think this is a whole new question....if they are petsmart carries the same stuff for the eheim that i need for the rena for less than 20. I will go thiss route if anyone has prior exp with swapping parts. I guess i need to know the diameter of the tubing req to hook the in/out to the can. there are 2 choices 16/22 mm and 12/16mm will one of these sizes work and do they have the same priming concept?