The purpose of this invention is to provide compositions useful for promoting the growth of calcareous organisms present in a closed system aquatic habitat. Particularly, to composition capable of efficiently delivering calcium and carbonate to the calcareous organisms. Most particularly, to a composition effective for enhanced delivery of aragonite to a closed system aquatic habitat where it dissociates into bioavailable supplements, such as, calcium, strontium, magnesium, and carbonate ions, whereby enhanced growth of the calcareous organisms is achieved.