HelloEric  Yes that  green veridgris stuff is the result  of the  the copper being is being dissolved/attacked . You probably noticed that the coper was also turning black. A simmilar reaction occurs with the brass tubing but as their is only a small ammount of copper in the brass the tubing is degraded and becomes brittle and porous quicker as only the zinc is left . Perhaps someone on here is a chemistry wizz and can give us en explanation ? Since I have started using the aluminium tubing i havent had any problems.

Regards

E.D