sap lines question gravity - not vaccuum

[tapdrinker]

I have a ton of fluid in the line but it's not moving. I had to remove the first tree tap(or furthest from the collection tank) to get it moving.
Anybody have this issue and how to fix it?

[Ultimatetreehugger]

Assuming adequate slope it means saps not running fast or at all on that line.

[maple flats]

When you open the line at the top you get sap, but you also pull contamination into the line, shortening your season. Don't rush it, the sap will flow when it's ready, impatience causes problems.