Seachem Reef Advantage Calcium 250g


Seachem Reef Advantage Calcium Concentrated, powder ionic calcium Maintains magnesium and strontium. Can be added directly to aquarium.


Reef Advantage Calcium

Reef Advantage Calcium is a non-caustic (pH 8.3–8.6) optimized blend of ionic calcium designed to restore and maintain calcium to levels found in natural seawater.

Calcium and carbonates are essential to all coral growth. If either becomes deficient, coral growth will cease, followed by a rapid decline in coral health.

Reef Advantage Calcium also includes magnesium and strontium in amounts proportionate to typical utilization ratios (100:5:0.1, Ca:Mg:Sr).

This allows one to maintain these two important elements while maintaining calcium. Unlike limewater (kalkwasser), Reef Advantage Calcium does not have a caustic pH and will not deplete magnesium.

Used as directed, it will not deplete alkalinity.



  • Use 5 g (1 level teaspoon) per 150 L (40 US gallons) twice a week. For precise dosing, use the Seachem Digital Spoon Scale.
  • Dissolve in at least 250 mL (1 cup) of freshwater. Check calcium every 2 weeks and adjust amount or frequency accordingly.


  • Check calcium level, then follow addition regimen above until calcium is adjusted to 380–420 mg/L.
  • Each 5 g/150 litres will raise calcium by about 12 mg/L. Quantity or frequency can be adjusted, but do not exceed 10 g/150 L per day. Thereafter, use as required to maintain calcium.


  • After determining the calcium consumption rate, set up a continuous drip system.
  • Use the following formula to determine how much to add to your top-off water: m=vc/400 (m=grams to add to top off water, v=volume of tank in litres, c=amount to raise calcium in mg/L).
  • [For reference: 1 gallon=3.8 liters, 5 g=1 teaspoon].

  • DO NOT OVERDOSE: Excess calcium may enhance the loss of carbonate alkalinity. Do not directly mix with any carbonate supplement. Best if calcium & carbonate additives are added on alternate days or at least 30 minutes apart.

    Guaranteed Analysis

  • Amounts per 1 gram
  • Calcium (Ca) (min) 335 mg
  • Calcium (Ca) (max) 347 mg
  • Magnesium (Mg) (min) 17 mg
  • Strontium (Sr) (min) 0.34 mg

  • Ingredients:

  • Calcium Chloride, Magnesium Chloride, Strontium Chloride