Can i use saltwater gravel in a freshwater fish tank?
It depends what the gravel is made of. If it’s inert, you can use it in a freshwater tank. If it’s calcium-based (i.e. limestone, crushed coral, etc) it will dissolve and raise the pH. This is good for a saltwater tank, but you generally don’t want that affect in a freshwater aquarium. edit: Aragonite will raise the pH. Unless you want to keep African cichlids, you shouldn’t use it for a freshwater aquarium. edit 2: I’m assuming that a modified iMac is only about 3-5 gallons, so your fish choices are pretty limited. Two or three male guppies would be okay in a small tank and can tolerate a pH up to around 8. It’s very important the pH is stable, though, so you should test the water frequently before you add fish to make sure that it isn’t fluctuating. If your water is already fairly hard the aragonite probably won’t make much of a difference, but if you have very soft water it might be too unstable.
Marine gravel is usually some sort of lime based rock. Crushed coral or limestone of some sort. While you can put it in fresh water it will tend to increase the hardness.and buffer the pH up. Now if your water is already hard, and has a pH around 8 anyway, then nothing will happen. However if you have lower pH water and are trying to keep fish that prefer low pH, then you can have problems because of that unstable pH. For an African Cichlid tank, it’s ideal. For an Amazon biotope with low pH fish – dont use it.
