<a href=showthread.php?s=&postid=13286637#post13286637 target=_blank>Originally posted</a> by AZDesertRat
WRONG. The rubber gasket always goes on the flange side of the bulkhead, regardless if its inside or outside the water. Never ever install the gasket on the threaded nut side of the bulkhead.
Bulkheads should be installed clean and dry, no lubricants or sealants should be used nor are they needed. Never support any piping or pumps with the bulkhead, always support any weight to relieve stress on the gasket and sealing surfaces. Teflon dope or tape is fine on the internal threaded PVC screw fittings but is not necessary on the sealing nut. Tighten the nut hand tight and maybe another 1/4 turn, do not overtighten as this is a common mistake that leads to leaks.