Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Need help with siphon!

Installed two 4" DWV siphons that ran fine for one week until they simultaneously(within a couple of hours)stopped. The head difference between the pond water level and the siphon outlet is 3 feet. The lift to get over the dam is now 5 feet instead of the original 2. The siphon inlets are not clogged. The lift section is a little "out of round" but definitely not crushed from pressure. I extended the siphon outlet, gaining another 4 vertical feet, but cannot get siphons started.

Whatcha think?

Just my opinion but you need more length on the outlet side.

For the pond type siphon, you need a 4 foot, or more, outlet drop from the water level. Be sure to use an elbow on the outlet, tilted upward, to prevent the water in a slower flow situation from flattening out in the pipe and allowing air to enter...

To restart, you need to fill the pipe as completely as possible. The best way is to use a vacuum pump at the highest pipe point. use a test plug to cap off the outlet. Another way is to cap both inlet and outlet, install a sealable Tee in the high point and bucket fill the pipe, cap off your tee, pull the inlet side plug, then pull the outlet plug...

Thanks guys,
Hey Rain, Do you think that I can install a backwater valve on the pond side at water level instead of a shut off? I'm thinking this will allow me to fill the top "t" then pull the plug on the siphon outlet to start. I have spent way too much time with bernoulli's equation, now I'm ready for round two, ding ding!

I missed this...sure, a backwater valve that actually works would make filling a LOT easier!