Instant Ocean Sea Salt is the most carefully formulated and universally preferred sea salt in the world. The #1 choice of hobbyists, public aquariums, and scientific research facilities, Instant Ocean Sea Salt has set the industry standard for quality, consistency, and value for more than 40 years. A nitrate-free and phosphate-free synthetic sea salt. It insures that even the most delicate marine fish, invertebrates and plants will thrive. Shipping weight: 3 1/2 lbs.