Good to be cautious but for future there are a couple points I might make. The chlorine in bleach is a liquid so it dilutes right away without stirring, etc. It reacts with anything organic it meets and part of it is gone that way. The reason it smells so strong coming out of the bottle is the chlorine becomes a gas and blows away. What that second part means is that it will blow away as soon as it is left out in the air. Soak to clean, rinse to dilute any left, and when it airs out, the chlorine is gone. If you can't smell it, there is a good chance there is more in your drinking water than on the rocks. I assume you are going to put that much rock in a new setup and you will be using a dechlor product (Prime,etc.) with the new water? Say there was some chlorine left on the rock. The dechlor takes care of it just like what comes with the tank water. No problem!