Seachem Reef Advantage Calcium 500 gm

Seachem Reef Advantage Calcium is a non-caustic, concentrated ionic calcium powder that also helps maintain magnesium and strontium levels.

• Concentrated, powder ionic calcium
• Maintains magnesium and strontium
• Can be added directly to aquarium

Reef Advantage Calcium™ is a non-caustic (pH 8.3–8.6) optimized blend of ionic calcium designed to restore and maintain calcium to levels found in natural seawater. Calcium and 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™ also includes magnesium and 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 lime water (kalkwasser), Reef Advantage Calcium™ does not have a caustic pH and will not deplete magnesium. Used as directed, it will not deplete alkalinity.

Part of maintaining stable reef chemistry — see our guide to KH (Alkalinity) for why this parameter is tracked closely alongside calcium and magnesium.

The Seachem Reef Advantage Calcium 500 gm replenishes calcium for coral skeleton growth — see our guide to Calcium & Magnesium for why it's tracked alongside magnesium and KH.

Compatibility

Marine and reef. It carries magnesium and strontium alongside the calcium, in the 100:5:0.1 ratio corals actually consume them, so a separate magnesium or strontium supplement is usually unnecessary while you are using it.

Do not mix it directly with a carbonate supplement. Dose them on alternate days or at least 30 minutes apart.

Dosage & Directions

Use 5 g (one level teaspoon) for every 150 L (40 US gallons) twice a week, dissolved first in at least 250 mL of fresh water. Each such dose raises calcium by about 12 mg/L.

Target 380–420 mg/L. Do not exceed 10 g per 150 L in a day — excess calcium pulls carbonate alkalinity down with it.

Freshness & Storage

Every batch we dispatch carries a minimum of 6 months' remaining shelf life. Store this product in a cool, dry place away from direct sunlight, with the cap or inner foil closed tightly after each use.

Returns & Replacement

Returns are accepted within 7 days of delivery, provided the item is unused and in its original packaging. Manufacturer-sealed items cannot be returned once the seal is broken, and sale-priced items are not refundable.

If your item arrives defective or damaged, message us on WhatsApp with your order number — or email us, if you would rather — and we will replace it. Approved replacements are delivered within 3 to 5 business days. Transit damage is covered by insurance on every shipment. If tracking shows delivered but nothing reached you, tell us within 72 hours, which is the reporting window Indian couriers allow. Damage caused during installation or use is not covered; replacement spares for such cases are chargeable.

Full terms are on our Cancellation & Returns page.