Pvc cement. I have many 40 gallon breeders and all have 2 one inch bulkheads, both on the back glass, one on left and one on right, both about 2 inches from the top. I found elbows to be too bulky and thats where i first tried it.I love a crafty solution! Did you use PVC cement to weld the two pieces together? Or are you using a different glue?