I have a fuge/sump setup and I am totally redoing it all and am curious how to run a a filter sock?I will run all pvc into and out of the fuge/sump Do I just put the sock in the 2 1/2 " hole on the top of my sump or does it get fastened to the return line,or does water just need to flow through it ..are the mostly the same size diamter inlet hole? .Pics would be great also thanks Sal