I have been trying to plumb my 210 AGA reef ready and the 3/4" bulkhead supplied for the return line does not fit standard 3/4 or 1" PVC. The bulkhead has "3/4 inch" threading and a smaller nipple. How do I hard plumb it when the threads don't fit in a 3/4 or 1 inch standard pvc part. Did they supply the wrong bulkhead? it is the only one supplied that fits through the smaller hole of the overflow. Any have this problem? thank you for any help.