I have the pump and a 15 gallon tank with a lid and otherwise solid top. Is there any particular way to insert the tube into the tank? I went to Home Depot to get a 1/4" (I.D.) rubber grommet or bushing - no luck. Local specialty plumbing supply store - no luck. There are plenty of wholesalers online, but I can't find anyone local in Austin. I was not expecting to get hung up on this part! Any suggestions? Thanks in advance!