Also known as kalkwasser, this is the most common precipitate found in saltwater tanks. It appears as a whitish dust or film on the tank walls and decorations, and while unsightly, it is actually a sign of good water chemistry. It mainly develops as sea salt mixes contain large amounts of calcium (Ca) and carbonate (CO3).
What is the white dusty material in salt water tank?
Calcium Carbonate (CaCO3) Precipitation