Seachem Reef Advantage Calcium

by Seachem

Selected Option: 1 lb
$34.99 (You Save 47%)
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Selected Option: 1 lb

Key Features

  • Raises calcium to natural seawater levels
  • Capable of raising 20 gallons of water by 25 ppm of calcium with only 1 teaspoon
  • Non-caustic and pH balanced (pH 8.3-8.6)
  • Maintains magnesium and strontium, will not deplete alkalinity


Seachem Reef Advantage Calcium is a non-caustic (pH 8.3-8.6) optimized blend of ionic calcium designed to restore and maintain calcium levels to those found in natural seawater. Note that if either calcium or carbonates become deficient, coral growth will cease, followed by a rapid decline in coral health.

In addition to calcium, Reef Advantage provides magnesium and strontium in amounts proportionate to typical utilization ratios (100:5:0.1, Ca:Mg:Sr), helping to maintain three critical elements at once. Unlike limewater (kalkwasser), Reef Advantage Calcium does not have a caustic pH and will not deplete magnesium. When used as directed, it will not deplete alkalinity.


BEGINNER: 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.

ADVANCED: Check calcium level, then follow addition regimen above until calcium is adjusted to 380–420 mg/L. Each 5 g/150 L 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.

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: m=vc/400 (m=grams to add to top off water, v=volume of tank in liters, 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 and carbonate additives are added on alternate days or at least 30 minutes apart.

Ingredients: Calcium Chloride, Magnesium Chloride, Strontium Chloride.

Guaranteed Analysis:

Calcium (Ca) (min) - 335 mg; (max) - 347 mg

Magnesium (Mg) (min) - 17 mg

Strontium (Sr) (min) - 0.34 mg


Brand Seachem
UPC 000116031301
SKU 313
Item Number L4805690915P48056
Size 1 lb
Weight 1.4 lbs.
Pkg Dimensions 8" (L) x 2" (W) x 2" (H)

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