Substrate is sometimes added for cosmetic reasons, but in a saltwater enviroment it can also play an important role in absorbing nutrients, such as in a Deep Sand Bed. In fish only tanks you can often use a larger grain size for ease of vacuuming the sand.
KNOP KORALlith is a natural and phosphate-free calcium granulate that originates from fossilized marine habitats. I
ZEOmag is a pure magnesium granualte. Mix with the coral gravel media at a rate of 10 – 30 % and fill into the calcium reactor. Coarse grain of 6 – 12 mm.