I just recently installed a 12" siphon pipe in my pond dam. It runs about 15 feet down the water side of the dam. When we put it together it seemed like we got a good connection - but I noticed today that the joint at the 22 1/2 degree elbow has slipped about an inch. This is the joint right under the 4" air intake tube. This means the glue did not bond it properly. The pond is now about half full - meaning the inlet pipe and about 7 feet of pipe is now submerged. I am not sure how this is going to be repaired since I cannot get down to the bottom to push the pipe up and re-glue it. I have a bad feeling that it may slip all the way off eventually - particularly when the siphon did kick in. So I had an idea - what if I used stainless steel screws and sunk them into the coupling and pipe to stop it from slipping off? I can do that right now while there is no water to that connection yet. Even if it was not perfectly airtight at that joint it would all be under water in a big rain and should mean that the siphon would kick on. Am I right or I am I dreaming? Thanks everybody!