Reef Advantage Calcium 250 g — Ionic Calcium pH 8.3 with Mg and Sr | Seachem

Seachem Reef Advantage Calcium is a non-caustic (pH 8.3–8.6) powdered ionic calcium supplement designed to restore and maintain calcium levels at natural seawater levels. It includes magnesium and strontium in proportions corresponding to typical usage ratios (100:5:0.1, Ca:Mg:Sr), allowing you to maintain these essential elements simultaneously without additional supplementation.

Main advantages

• Concentrated ionic calcium powder — 5 g per 150 L increases calcium by 12 mg/L
• Non-caustic pH (8.3–8.6) — no pH fluctuation unlike kalkwasser
• Includes magnesium and strontium in typical usage ratios (100:5:0.1, Ca:Mg:Sr)
• Does not deplete magnesium or alkalinity when used as directed
• Economical powder format, compatible with pre-mixed solution dosing pumps

Use in reef aquariums

Calcium and carbonates are essential for all coral growth. If either becomes deficient, growth ceases, followed by a rapid decline in coral health. Unlike kalkwasser, which has a caustic pH and depletes magnesium, Reef Advantage Calcium mixes at a safe pH of 8.3–8.6. Seachem recommends maintaining calcium between 380 and 420 mg/L with an alkalinity between 3 and 6 meq/L (8–17 dKH).

Dosage

• Beginner: 5 g (1 level teaspoon) per 150 L (40 US gallons), twice a week. Dissolve in at least 250 ml (1 cup) of fresh water.
• Advanced: Dose until reaching 380–420 mg/L. Each 5 g dose per 150 L increases calcium by 12 mg/L. Do not exceed 10 g per 150 L per day.
• Expert: determine the consumption rate and configure a continuous drip. Formula: m = v × c ÷ 400 (m = grams, v = volume in liters, c = increase in mg/L).

Ingredients and guaranteed analysis

Ingredients: calcium chloride, magnesium chloride, strontium chloride.

• Calcium (min): 335 mg/g — (max): 347 mg/g
• Magnesium (min): 17 mg/g
• Strontium (min): 0.34 mg/g

Preparation for dosing pump

To create an automated dosing solution, dissolve 1 teaspoon (5 g) in 25–30 ml of water. According to Seachem, 165–200 g can be dissolved in 1 L of RO/DI water. Calculate the weekly amount based on the consumption rate and divide by 7 for the daily dosage.

Manufacturer's precautions

• Do not exceed 10 g per 150 L per day
• Excess calcium can accelerate the loss of carbonate alkalinity.
• Do not mix directly with a carbonate supplement — alternate days or wait at least 30 minutes
• Causes serious eye irritation — keep out of reach of children, avoid skin contact

Available formats

• 250 g
• 500 g
• 1 kg
• 4 kg

Why choose Reef Advantage Calcium from ReefSolution?

For complete reef supplementation, combine Seachem Reef Advantage Calcium with Seachem Reef Carbonate for alkalinity and Seachem Reef Advantage Magnesium for magnesium. Monitor your levels with the Salifert Calcium Test Kit or the Hanna Checker Calcium. For secondary dosing of bioavailable organic calcium, add Seachem Reef Calcium.

Frequently Asked Questions

What is the difference between Reef Advantage Calcium, Reef Complete and Reef Calcium?

Reef Advantage Calcium (powder) and Reef Complete (liquid) are both ionic calcium supplements with magnesium and strontium—the choice depends on whether you prefer powder or liquid. Reef Calcium is an organic calcium polygluconate for maintenance, not for increasing levels.

Can Reef Advantage Calcium be used with a dosing pump?

Yes. Dissolve 165 to 200 g in 1 L of RO/DI water to create a concentrated solution. Calculate the weekly dose based on your system's consumption and divide by 7.

Why is Reef Advantage Calcium preferable to kalkwasser?

Unlike kalkwasser, Reef Advantage Calcium mixes at a non-caustic pH of 8.3–8.6, does not deplete magnesium, and includes strontium in natural proportions. Dosage is more precise and predictable.