Me either. You do not want water flowing straight into an open bulkhead hole. If any kind of critter gets in there (snail, fish, hermit, etc) and plugs the line, you will then have a flooded main tank since your return pump is still returning water, but none is making back to the sump. As Mrc stated, you want to have a very short piece of pipe coming out of the bulkhead, then a 90 pointing straight up, and a pipe coming up out of that with a strainer on top (hence, "standpipe"). The height of the standpipe determines the water level in the tank.