I've noticed on the last couple of backwashes, I have a small leak coming out of the connection between the filter and the pump. It only happens when I'm backwashiing. A large drop of water will form at the bottom of the union and eventualy drops off onto the side of the filter. It doesn't happen when the pump in running normally. I try to backwash for 2 minutes and rinse for 30 seconds.
What would be a quick and easy fix to prevent it from leaking? I really don't want to have to take the pipe off and reseal it. Plumber's putty, perhaps?