Reef Advantage Calcium 1 kg — Ionic Calcium pH 8.3 with Mg and Sr | Seachem

Seachem Reef Advantage Calcium in a 1 kg format is a non-caustic (pH 8.3–8.6) powdered ionic calcium supplement designed to restore and maintain calcium levels in reef aquariums. Its formula includes magnesium and strontium in proportions corresponding to typical usage ratios (100:5:0.1, Ca:Mg:Sr). The 1 kg format offers excellent value for money for aquarists who regularly dose calcium, especially those with high-consumption SPS coral systems.

Main advantages

• Concentrated ionic calcium powder — 5 g per 150 L increases calcium by 12 mg/L
• Non-caustic pH (8.3–8.6) — without risk of fluctuation, unlike kalkwasser
• Includes magnesium and strontium in natural ratios (100:5:0.1, Ca:Mg:Sr)
• 1 kg format — economical for regular dosing and high-demand systems
• Compatible with pre-mixed solution dosing pumps

Use in reef aquariums

Calcium is essential for the formation of the skeleton in SPS and LPS corals and coralline algae. A calcium deficiency causes growth to stop, followed by a rapid decline in coral health. Reef Advantage Calcium differs from kalkwasser in that it maintains a safe pH and the ability to simultaneously maintain magnesium and strontium levels without additional supplementation. 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 quantity based on the consumption rate and divide by 7 for the daily dosage. The 1 kg format allows for the preparation of several liters of concentrated solution in advance.

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 a complete reef program, combine Seachem Reef Advantage Calcium with Seachem Reef Carbonate for alkalinity and Seachem Reef Advantage Magnesium for magnesium. Monitor your parameters with the Salifert Calcium Test Kit or the Hanna Checker Calcium and automate your dosing with the Kamoer X1 Pro Dosing Pump.

Frequently Asked Questions

Is the 1 kg format advantageous for automated dosing?

Yes. The 1 kg format allows you to prepare several liters of concentrated solution for dosing pumps. Dissolve 165 to 200 g per liter of RO/DI water and dose daily according to your system's consumption.

Does Reef Advantage Calcium replace the need to test for strontium and magnesium?

Partially. The product includes Mg and Sr in typical usage ratios (100:5:0.1). For high-demand systems, supplementation with Seachem Reef Advantage Magnesium may be required depending on test results.

How long does a 1kg format last?

At a starting dosage of 5g twice a week for a 150L aquarium, a 1kg package lasts for 100 doses, or approximately 50 weeks. The duration decreases with systems that have high calcium consumption.