Product DescriptionReef Advantage Strontium™ restores and maintains strontium to levels found in natural sea water. Strontium is utilized by corals in the same manner as calcium and holds a similar importance in maintaining a vigorous level of growth. It is most useful in densely populated aquariums requiring a continuous supply of strontium. Reef Advantage Strontium™ is a highly concentrated (30,000 ppm), ionically balanced strontium supplement.Strontium occurs in natural seawater at a concentration of about 8 to 10 mg/L. It is chemically very similar to calcium, and many organisms incorporate it in their skeletons along with calcium. Its addition to reef aquariums aids the growth of corals, coralline algae and other organisms that lay down a calcereous skeleton or shell, including tridacnid clams.Sizes: 70 g, 300 g, 600 g, 1.2 kg, 4 kg, 20 kgWhy It's DifferentUnlike other strontium chloride products, Reef Advantage Strontium™ is formulated so that it can be added directly to the aquarium. Competing products require one to mix a separate solution before adding it to the system.DirectionsBEGINNER: Use 8 g (1 level teaspoon*) per 150 L (40 gallons*) twice a week. May be added directly to aquarium. ADVANCED: Check strontium level, then follow addition regimen above until strontium is adjusted to 8–12 mg/L. Each 8 g/150 L will raise strontium by about 2 mg/L. Amount or frequency can be adjusted as needed. Thereafter, use as required to maintain strontium. EXPERT: After determining the strontium depletion rate, set up a continuous drip system. Use the following formula to determine how much to add to your top-off water: m=vs/30 (m=grams to add to top off water, v=volume of tank in liters, s=amount to raise strontium in mg/L). For example, if you want to raise strontium by 6 mg/L in a 200 liter aquarium, then you would add (200x6)/30=40 g into the top-off water. [For reference: 1 gallon* = 3.8 liters]. Notes: Use the Reef Status: Strontium™ to check strontium levels.DO NOT OVERDOSE: Excess strontium may enhance the loss of carbonate alkalinity. Do not directly mix with any carbonate supplement. Best if strontium & carbonate additives are added on alternate days or at least 30 minutes apart.