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Seachem Reef Advanatage Calcium

Designed to restore & maintain calcium to levels found in natural seawater. Maintains magnesium and strontium.

Calcium & 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 is a non-caustic (ph 8.3-8.6) optimized blend of ionic calcium. It also includes magnesium & 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), it does not have a caustic pH and will not deplete magnesium. Used as directed, it will not deplete alkalinity.

To prevent coral problems, you must provide calcium Reef Advantage Calcium and carbonates (Reef Builder or Reef Carbonate).

Hint: If used with Reef Calcium, it is not necessary to exceed 380 mg/L total calcium.

Use Reef Status™: Calcium to measure calcium.


  • Beginner: Use 1 level teaspoon per 150 L (40 gallons*) twice a week. Dissolve in at least one cup of freshwater. Check calcium every 2 weeks and adjust dose or frequency accordingly.
  • Advanced: Check calcium level, then follow dosing regimen above until calcium is adjusted to 380–420 mg/L. Each dose will raise calcium by about 12 mg/L. Size or frequency of dose can be adjusted, but do not exceed 25 mg/L per day. Thereafter, use as required to maintain calcium.
  • Expert: 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: t=0.002vc (t=teaspoons to add to top off water, v=volume of tank in gallons, c=amount to raise calcium in mg/L). For example, if you want to raise calcium by 25 mg/L in a 50 gallon* tank, then you would add 0.002x50x25=2.5 teaspoons into the top-off water.

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.

$7.27 ea
Seachem Reef Advantage Calcium, 250 Gm
$12.49 ea
Seachem Reef Advantage Calcium, 500 Gm