I'm sure there are more people on here that know more then I do and have more experience setting up 55 gallon barrels as a moving bed filter system!!!! Does anyone know what the push in connection things are called where you put a rubber gasket between the barrel and the pvc piping. I'm trying to order some and have no idea how or what there called? Can someone please help me so I don't have to jerry rig it with just silicone like I originally planned? Please help me figure out what is the best way to connect the 3 barrels thanks!!!!