Can I use flintstone in an aquarium?
Can I put flintstone in a freshwater aquarium after I soaked it in vinegar for removing the lime crust?
flintstone mainly consists of silicium dioxide and does not contain lime. Removing lime with an acid is therefore not necessary, rinsing and removing attached dirt is sufficient. A white crust on flintstone does not consist of lime although it looks similar.
If the rock actually contains lime (in that case it will foam if you drip some sufficiently strong acid on it, e.g. sera pH-minus), it is not a flintstone. However, there are no general objections against lime containing rock. The hardness may increase somewhat in acidic water, but usually not so strongly that you could not keep it under control with usual water changes. Very strong CO2 fertilization in combination with lime rock will increase hardness more strongly (remember calcium reactors in saltwater aquariums!).
Dr. Bodo Schnell