Albeit low at 0.06 ppm according to Hanna. This is coming out of my RO/DI (5-stage) and is the water I do my water changes with. As some of you know, I have already been battling copper infusion in my DT for quite some time (currently at 0.09/Hanna). But given the +/- 0.03 error factor, are my make-up water numbers high enough to really worry about or should I throw some Cupisorb in a filter sock to get it down some more?
