cemented rock

[sphelps]

My understanding it that it will take 6 weeks to a few months to cure in fresh water and that's with daily water changes. It's recommended to use a separate container or bathtub other an aquarium for this reason. For small pieces you can place them in a toilet tank for a faster cure rate.

As others have mentioned measuring the PH of the water will tell you when it's cured and give a better idea on the progress.