Crushed coral can be great for saltwater or freshwater aquariums. However there are some cons that may outweigh the benefits. Refer to the bulleted lists below.
Crushed Coral Pros :
- Helps stabilize PH by increase KH and GH
- Will never need to be replaced (if vacuumed regularly)
Crushed Coral Cons :
- Can develop small pockets of fish waste and food causing nitrates to rise.
- Needs to be vacuumed a minimum of once a week. Therefor crushed coral would not be a good choice for a planted aquarium.
- Not easily penetrated by fish and invertebrates that like to dig and hide under substrate.