Black gunk in old drops worse in conifers.

[blissville maples]

So, replacing drops and varmit repair, noticed drops in lower bush where hemlocks very thick are filthy. even the semi rigid lateral lines are spotty with mildew and overall gunkiness. but once uptop no hemlocks, its normal. thinking lack of sunlight?? anybody have any other similar instances of this?

[adk1]

Yup I have noticed the same thing must be lack of sunlight etc

[blissville maples]

makes me wonder about clear tubing?? wonder if anyone has tried any with any noticeable differences. potentially not too many people with this issue just hate to run nice sap thru that