[lysacat]

I have salt and fresh water aquariums, I do use the dark colored gravel in my fresh water tank but if you have any problems keeping your pH up in your tank then Aragonite gravel (crushed coral) would be ok to help keep the pH up. The sand won't be good if you use an under gravel filter because it will all go through the slits in the grate under the gravel. Check in your area though and see if there is a real aquarium store or pet store. Petsmart is not very knowledgeable about things. Good luck.