1 level measuring spoon increases the strontium level of 10 gallons by about 2 ppm. The natural concentration of seawater is 8 ppm. In a reef aquarium the concentration of strontium decreases quickly through biological processes, precipitation and by the use in calcareous animals. A basic dosage of 1 level measuring spoon per 50 gallons every two weeks is recommended. In an aquarium with a high population, the dosage can be as much as 1 level measuring spoon per 50 gallons each week. High strontium concentrations in the aquarium may damage corals. Always be sure to monitor the strontium concentration with a Strontium Test.