Reef Advantage Calcium 250 g to 4 kg — Ionic Calcium Powder pH 8.3 with Mg and Sr - Seachem

Seachem Reef Advantage Calcium — powdered ionic calcium, 250 g to 4 kg

Reef Advantage Calcium from Seachem is an optimised blend of ionic calcium in powder form, built to restore and maintain calcium at the levels found in natural seawater. It comes in four sizes: 250 g, 500 g, 1 kg and 4 kg.

What sets it apart: it mixes to a non-caustic pH of 8.3 to 8.6. Unlike limewater (kalkwasser), it will not push your pH around and will not deplete magnesium. Used as directed, Seachem states it will not deplete alkalinity either.

Why calcium matters

Seachem puts it plainly: calcium and carbonates are essential to all coral growth. If either becomes deficient, growth stops, followed by a rapid decline in coral health.

Reef Advantage Calcium also delivers magnesium and strontium in amounts proportionate to typical utilisation ratios (100:5:0.1 — Ca:Mg:Sr). You maintain three elements while dosing a single product.

On concentration, Seachem gives a useful benchmark: a single teaspoon raises 20 US gallons by 25 ppm of calcium.

Dosing by experience level

Beginner. 5 g (1 level teaspoon) per 150 L (40 US gallons), twice a week. Dissolve in at least 250 mL (1 cup) of freshwater. Check calcium every 2 weeks and adjust amount or frequency accordingly.

Advanced. Test your calcium level, then follow the regimen above until calcium is adjusted to 380–420 mg/L. Each 5 g per 150 L raises calcium by about 12 mg/L. Amount and frequency can be adjusted, but never exceed 10 g per 150 L per day.

Expert. Once you know your consumption rate, set up a continuous drip system. Seachem's formula: m = v × c ÷ 400 (m = grams to add to top-off water, v = tank volume in litres, c = calcium increase wanted in mg/L).

Seachem recommends a calcium level of 380–420 mg/L with alkalinity between 3 and 6 meq/L (8–17 dKH), and advises making large adjustments slowly so you neither overshoot nor shock corals and inverts.

Mixing a stock solution for a dosing pump

Seachem reports successfully dissolving 1 teaspoon in 25 to 30 mL of liquid — which works out to 165 to 200 g per litre of RO/DI water. The manufacturer notes these are estimates based on its own findings and that results may vary in a larger volume of water.

To get your daily dose: divide the weekly calcium increase you want by 12 ppm, multiply by 5 g, scale that to your tank volume against 150 L, then divide by 7.

Manufacturer's cautions

• Do not exceed 10 g per 150 L (40 US gallons) per day.
• Excess calcium may enhance the loss of carbonate alkalinity.
• Never mix directly with a carbonate supplement. Seachem advises dosing calcium and carbonate on alternate days, or at least 30 minutes apart.
• Causes serious eye irritation. Keep out of reach of children, avoid contact with skin.

Guaranteed analysis and ingredients

Per gram of product:

• Calcium (Ca): minimum 335 mg, maximum 347 mg
• Magnesium (Mg): minimum 17 mg
• Strontium (Sr): minimum 0.34 mg

Ingredients: calcium chloride, magnesium chloride, strontium chloride.

The four sizes

At the beginner dose of 5 g, here is what each size represents in number of doses:

• 250 g — 50 doses
• 500 g — 100 doses
• 1 kg — 200 doses
• 4 kg — 800 doses

At two doses a week on a 150 L tank, a 1 kg tub covers roughly two years. That is our own arithmetic from the official dose — Seachem publishes no service life per size, and your real consumption depends on your coral load.

Why buy it from ReefSolution

Calcium never works alone. On the alkalinity side, Seachem pairs Reef Carbonate with Reef Advantage Calcium — remembering to dose them on alternate days or 30 minutes apart. If your tests show magnesium dropping faster than calcium, Seachem names its Reef Advantage Magnesium as the supplement to add. And to hold a calcium level that is already on target rather than raise it, Reef Calcium plays a different role — explained in the FAQ below.

• In business since 1999, over 118,000 orders processed since 2010.
• Store in Laval — we can show you the product and answer your dosing questions in person.
• Shipping across Canada. Free shipping available depending on order total.

Frequently asked questions

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

Seachem is categorical: Reef Complete is the liquid version of Reef Advantage Calcium. Both are ionic calcium supplements that also provide magnesium and strontium in typical utilisation ratios. The choice comes down to preference: liquid doses with no pre-mixing, powder is more economical.

And compared to Reef Calcium?

They are completely different products. Reef Advantage Calcium is an ionic calcium, highly concentrated and economical, used to raise calcium. Reef Calcium is an organic calcium (poly-gluconate) bound to an easily metabolised carbohydrate, so corals spend less energy using it, and it is meant to maintain a calcium level already in range. Seachem suggests Reef Advantage Calcium as your primary supplement and Reef Calcium as the secondary one.

Do I still need to dose magnesium and strontium separately?

Normally no: Seachem writes that if Reef Advantage Calcium is used to maintain calcium, other strontium and magnesium supplements are not necessary. The manufacturer adds that if usage or precipitative loss drives magnesium or strontium down faster, you may then employ Reef Advantage Magnesium or a strontium supplement. Your test results decide.

How do I prepare it for a dosing pump?

Seachem reports dissolving 1 teaspoon (5 g) in 25 to 30 mL of liquid, roughly 165 to 200 g per litre of RO/DI water. Then calculate your weekly requirement from your consumption rate and divide by 7 for the daily dose.