Reef Complete is a concentrated (160,000 mg/L) optimized blend of ionic calcium designed to restore and maintain calcium to levels found in natural seawater without affecting pH. Calcium and carbonates are essential to all coral growth. KEY FEATURES: Liquid ionic calcium source Most concentrated calcium supplement on the market (160,000 mg/L) 100% soluble. Be wary of products that are milky white or need to be shaken DIRECTIONS: Beginner Use 1 capful (5mL) per 80L (20 US gallons) twice a week. Check calcium every 2 weeks and adjust amount or frequency accordingly. Advanced Check calcium level, then follow addition regimen above until calcium is adjusted to 380-420 mg/L. Each 5 mL/80 L (20 US gallons) will raise calcium by about 10 mg/L. Quantity or frequency can be adjusted, but do not exceed 12.5 mL/80 L (20 US gallons) per day. Thereafter, use as required to maintain calcium.