what is causing dark green streaks in bottom of toilet
We recently installed (and mostly love) a Coroma dual-flush toilet. In the past few weeks, I've noticed there are dark green streaks in the corners at the bottom of the bowl. They are almost hidden, toward the trap I guess, below the water line. It's not from our "waste." It's not hard to scrub away with a brush, but it keeps coming back. Any idea what's causing this, and how to deal with it? Thanks!