As you can see, when the modified barbed T is inserted into the PVC drain pipe, it sits at an angle. If you don't do this, your funnel will run into the barbed T and your bottom end cap will not seat all the way against the end of the drain pipe and you will most likely end up with leaks. Use epoxy on the inside and outside to attach the barbed T, silicone will be too flexible and will break loose as soon as you try to attach your drain line.