This has probably been talked about before. I have not searched too much in the archives. I bought a bag of river pebble at Menards. I scooped up a jar full, washed it, and filled the bar with vinegar. It bubble profusely for a couple hrs then the bubbles pretty much quit. Is that stone usable? How much bubbling is too much bubbling?
In order to use those rocks you would have to seen no bubbles at all. so I will recommend that you don't use that rock. if that is not an option then keep exposing the rock to vinegar until the rocks no longer create any bubbles.