Quote Originally Posted by Sugar Bear View Post
But somehow the effectiveness of the sap column and or the flow of the lower taps/drops within the column seem like they are being hindered.
The lower taps will mostly be "hindered" by the lack of vacuum. In other words, the pressure differential from the inside of the tree to the tubing is much lower compared to the taps higher up on the hill getting strong vacuum. Since sap flow is linearly related to vacuum level, it is not unexpected that the trees lower down (not getting much if any vacuum) will run far less.