thanks jeff --i really hope that comment helps some folks on this forum--Otto was helpful in discussing and offering his opinions in the past so i am hoping he sees these posts. Another thing i did this year is to put a 8" valve in my siphon pipe on the pond side of the dam (originally put it on back side but it forced my siphon pipe to leak on the back due to pressure)so i put it on the front top and have a 8" pipe with cap to allow me to get water tool down to it to open and close as needed. no need to open yet. that should allow me to fill the pond to the very top and use just the run around or in heavy rains open the valve some as well if i have to. my goal is to be able to go into next summer when my spring stops with a pond full of water. this pond was built mainly for aesthetics but also to occasionally fish. my original dirt mover came down and dug all around the site in 12 or so locations to see what kind of clay we had and assured me what we had was good. afterward he said "well we knew the site wasn't the best". grrr.
If your pipe was leaking on the backside, I would get those joints sealed or it may not siphon at all, just drain like a normal pipe. There is actually very little "PSI" pressure on the pipe, just the vertical weight of the water.
that should allow me to fill the pond to the very top and use just the run around or in heavy rains open the valve some as well if i have to. my goal is to be able to go into next summer when my spring stops with a pond full of water. this pond was built mainly for aesthetics but also to occasionally fish. my original dirt mover came down and dug all around the site in 12 or so locations to see what kind of clay we had and assured me what we had was good. afterward he said "well we knew the site wasn't the best". grrr. 
