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Thanks for the post! The Onyx Gravel and the Onyx Sand are very carbonate rich substrates that will provide a slow release that will boost alkalinity and pH. This will act as a safety net, as well as, buffering the pH/alkalinity up by a couple of units, which is very beneficial in an African Cichlid tank where the pH and alkalinity need to be on the higher side.
I hope this helps! Let us know if you need further assistance!
Hello! Cichlids can move the substrate if they are flashing against the substrate, or deliberately trying to move it. However, neither the Onyx sand nor the Onyx gravel are prone to being churned up by movement on their surface. Sands in general are much more prone to being moved around in general because their individual particle size is much smaller than a gravel, so they can be moved much more easily. If you want your fish to be able to dig around in the substrate, I would recommend the Onyx Sand, but if you are looking for a substrate that will not be prone to "sandstorms" I would recommend the Onyx gravel.
I hope this helps!
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