ok, back to the original post, first of all, I seriously doubt some floral arranging sticks would affect the pH of the water, also wonder how wood, which makes pH drop would be making the pH rise.
the Silver streak will slowly buffer your water back up to around 8.0 - 8.5 for the first 2-3 years of use.
when you say slowly rising what do you mean???, 0.1-0.2 over the course of a week, although not perfect is still ok