Seachem Reef Fusion 1 – Concentrated Ionic Calcium for Thriving Corals

Give Your Corals the Calcium They Crave

Corals can't grow when calcium and alkalinity drift out of range, and hitting those targets by guesswork leaves your reef stalling instead of flourishing.

Reef Fusion 1 is the first half of Seachem's two-part reef system, delivering a concentrated 100,000 mg/L of ionic calcium plus biologically appropriate magnesium, strontium, boron, iron, manganese, and molybdenum. Paired with Reef Fusion 2 in a simple 1:1 ratio, it makes maintaining optimal parameters for stunning coral growth easy to measure and easy to trust.

Reef Fusion 1 comes from Seachem Laboratories, a chemistry-driven company founded in 1979 in Madison, Georgia, where products are developed in-house by chemists rather than simply blended to a formula. That scientific approach shows in how Reef Fusion 1 is built to work as one coordinated part of Seachem's larger reef system for calcium, alkalinity, magnesium, trace elements, and coral nutrition — so the calcium you dose slots into a program designed to keep every parameter in balance together.

1. Shake well, then add 1 mL of Reef Fusion 1 per 25 L (6.5 US gallons) to a high-flow area near a powerhead.
2. Wait a few minutes, then add Reef Fusion 2 the same way at an opposite location in the tank.
3. Dose every 1-2 days, keeping calcium at 380-420 mg/L and alkalinity at 3-6 meq/L.

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Why Seachem Reef Fusion 1

• Delivers the calcium half of a two-part system: supplies ionic calcium plus magnesium, strontium, boron, iron, manganese, and molybdenum to hold calcium and alkalinity in the ranges corals need to build skeleton.
• Concentrated for real reefs: a concentrated 100,000 mg/L of ionic calcium means small, measurable doses, with each dose contributing 4 mg/L of calcium and 0.176 meq/L of alkalinity.
• Designed to pair 1:1 with Reef Fusion 2: the two formulas are engineered to be dosed together in equal amounts at opposite locations, keeping the reef system in balance.
• Ionic, bioavailable form: calcium and supporting elements are supplied in biologically appropriate ionic form that corals and coralline algae can readily use.

Best For

Reef aquariums with actively calcifying inhabitants — SPS and LPS stony corals, clams, and coralline algae — where consistent calcium and alkalinity are essential for continued growth and coloration.

FAQ

Which Reef Fusion do I pair this with? Reef Fusion 1 is designed to be dosed alongside Reef Fusion 2 in a simple 1:1 ratio, added a few minutes apart at opposite locations in the tank. Never mix the two formulas directly.

How do I know how much to dose? Test your water and keep calcium around 380-420 mg/L and alkalinity between 3-6 meq/L. Start at 1 mL per 25 L (6.5 US gallons) every 1-2 days, and adjust based on your test results without exceeding 4 mL/25 L per day.

Is it reef-safe? Yes. Reef Fusion 1 supplies calcium and trace elements in biologically appropriate ionic form and is formulated as part of Seachem's coordinated reef system for coral and invertebrate aquariums.

What It Does

Supplies a concentrated 100,000 mg/L of ionic calcium along with essential marine compounds — magnesium, strontium, boron, iron, manganese, and molybdenum — to maintain optimal water parameters for continued coral growth and development. Each dose contributes 4 mg/L of calcium and 0.176 meq/L of alkalinity.

Directions

The formula can be dosed in the aquarium every 1-2 days. Shake well before using. Add 1 mL of Reef Fusion 1 per 25 L (6.5 US gallons) of aquarium water. The cap of the bottle holds 5 mL. Add the mixture to a high flow area of the tank such as near a powerhead for increased current. Wait a few minutes and then add Reef Fusion 2 following the same procedure, 1 mL per 25 L (6.5 US gallons) and shake well. It is recommended that the two formulas be carefully added to opposite locations in the aquarium. This dose contributes 4 mg/L of calcium, and 0.176 meq/L of alkalinity. Never mix Reef Fusion 1 with Reef Fusion 2 directly. Calcium levels should be maintained around 380-420 mg/L and alkalinity between 3-6 meq/L. The size and the frequency of these dosages can be increased if the dosing schedule has been unable to properly maintain calcium and alkalinity in these ranges. Be careful not to exceed 4 mL/25 L (6.5 US gallons) per day.

Available Sizes

500 mL