Too much water in column will simply pull a vacuum bubble on the top and prevent a siphon. Think of a barometer, 30 inches for mercury sound familiar? It takes 34 feet of water to make a barometer, and you can test that with a capped pipe full of water stood on end, then accurately measure air pressure by measuing the water column height.
http://en.m.wikipedia.org/wiki/Atmospheric_pressureYour biggest biggest problem I think is trying to get all that water moving before air creeps back up the outlet end. It takes a while to get that much water up to speed to prevent air from back feeding. Put a large bucket full of water at the outlet and submerge the pipe end, then open the valve. Air can no longer get up the pipe. Once the water is moving, the momentum can really push it over the hump.
Best bet is to prime the siphon from the higher water side to get it started.
Getting the flow started with no air was the easy part, I put a 45 on the outlet with 2' of pipe which would duplicate the pipe being in a bucket. I also had an air bleed at highest elevation with a 2' extension, when the water stayed within an inch of the top of that extension, air was expelled, I even put a 5 gallon bucket under the air bleed valve and this was when I discovered something wasn't right. When I accomplished 2-3 successful airless fills I had the wife go down to the valve to open so I could watch the pipe that was over the bucket which sagged on both sides of the bucket when going into "airless state" My fill valve is actually just a few feet from where this bleed was so I had full view of this sag meaning that at highest elevation the sag confirmed no air considering I drop 50' gracefully toward outlet and more abruptly towards the source. Opening the bleeder 3 minutes after system hold would confirm no air had traveled to highest elevation.
when I told the wife to open the valve, the sag would immediately disappear to a perfect straight pipe in both directions ( the Vacuum ) Had I not had the swing check on the source side, I may have been able to poach an egg inside the pipe at the air bleed
Out of frustration, this is where I headed here and posted, had I just googled necessities of a siphon it would have been game over and I wouldn't be embarrassed that in 50 years of life I had always "presumed" a siphon was regulated by volume, drop, size, length, type of water being somehow molecularly bound as to create the siphon. I now know to replace the word siphon with vacuum and we're good! With the amount of systems dealing with water and some of the things we achieve here, I am in complete shock that my cranial hard drive had deleted the 30' rule if in fact it had ever been there in the first place.......
