Instructions: Shake product well before using. Add 5 ml (1 capful) of product per 50 US-gallons of aquarium water every other day or as needed to maintain the calcium concentration within a range of 412 - 450 ppm. 500 ml treats up to 5000 gallons. LIQUID REEF may temporarily cloud aquarium water after addition, therefore it is recommended that the product be dosed at night.