Well I can't tell about any fizzin' because anything I pour on the rocks, instantly disappears (into the pours). Don't detect any fizzin' but won't swear that it ain't happening. Can't I just put the rocks in a bucket of my (well) water and see if the KH or GH changes ....you know a before and after test? If I'm doing frequent water changes (say monthly), any influence the rocks are going to pose would have to happen quickly to be a problem.
