In my experience, just removin water won't actually help too much with removing the bleach. For example, if you've ever dyed clothing, no matter how much you rinse it the bleach stays there.
First you need to neutralize the bleach. The easiest way to do it is to get a whole lot of hydrogen peroxide and soak your rock in it for a day or two. That changes the bleach into chloride, more water, and oxygen gas. I'd change out the hydrogen peroxide a few times. once you don't see any bubbles anymore, the bleach is probably mostly gone. THEN use dechlorinated water with lots of water changes for a long period of time-- put an excess of dechlorinator in to remove any choramine that might have formed from neutralizing the bleach.
best of luck!