Problems with gravity lines HELP PLEASE

[Darkhollow Sugar Bush]

We installed 1600' 3/4 mainline with a lot of slope. the top of the line is probably 300' higher than where it goes into the storage tank. It seems that the sap is bunching up at the saddles. Does anyone know if the mainline should be vented at the top???? My dad said its just like filling a three foot hose full of water and putting your thumb over the end and lift it above your head. The water wont come out until you move your thumb. Any help would be appreciated thanks.

[jgavic]

How many taps on it?

[Darkhollow Sugar Bush]

There is about 150 right know still tapping trying to get 400 on it

[jgavic]

I don't understand why the sap is bunching up at the saddles? You should have plenty of venting coming from the end of the mainline (traveling on top of the sap). If you set up your laterals correctly you should get some great natural vacuum.

[Darkhollow Sugar Bush]

Is the end of the mainline supposed to be vented. There is no vent anywhere, the only open spot is at the tank at bottom end.It seems like there is a lot of vacuum

[Thompson's Tree Farm]

Don't vent it! A vent only leads to lower production due to bacterial contamination. As soon as signifigant sap runs, it will run into your tank.