If you can smell it, chlorine is present! Soak the rock, and then use a total chlorine test kit to check the water after 48 hours. Use Amquel at twice the required amount to neutralize the chlorine.
Amquel is good, as if any is left, it is neutral, and won't hurt your fish.
Amquel is good, as if any is left, it is neutral, and won't hurt your fish.