Seachem Reef Fusion 1

Seachem Reef Fusion 1 is the calcium half of Seachem's Reef Fusion two-part dosing system. It supplies ionic calcium along with magnesium, strontium, and a full blend of trace elements, giving corals the building blocks they need for steady skeletal growth and vivid color. Available from a 500 mL bottle up to a 4 L value size.

Why Reef Fusion 1

• Restores the calcium that hard corals, clams, and coralline algae pull from the water
• Also supplies magnesium, strontium, and the trace elements a growing reef depends on
• Designed as the part 1 (calcium) component of the Reef Fusion two-part system
• Dose alongside an alkalinity source so calcium and carbonate stay in balance
• Concentrated liquid, offered in four sizes from nano reefs to large systems

How to Dose

Add Reef Fusion 1 as directed for your tank volume to hold calcium in the ideal 380 to 450 mg/L range, and pair it with Reef Fusion 2 so calcium and alkalinity rise together. Raise calcium gradually, no more than about 25 mg/L per day, and test regularly. Heavily stocked SPS systems consume more, so dose to your tank's measured uptake.

The Two-Part System

Reef Fusion 1 and Reef Fusion 2 are built to work together: part 1 carries calcium and trace elements, while part 2 carries carbonates and magnesium for alkalinity. Dosing both keeps the major and minor ions of natural reef water in their correct ratios. If you would rather use a single all-in-one calcium source, Reef Complete is another option we stock.

Specifications

Recommended Pairings

• Seachem Reef Fusion 2: the alkalinity and carbonate half of the system
• Seachem Reef Complete: all-in-one calcium supplement
• Seachem Reef Builder: raises carbonate alkalinity on its own
• Seachem Reef Advantage Magnesium: keeps magnesium in range so calcium and alkalinity stay stable
• Browse the full Seachem lineup and our reef additives and supplements

Frequently Asked Questions

Do I have to use Reef Fusion 2 with this?
For a balanced reef, yes. Reef Fusion 1 raises calcium and Reef Fusion 2 raises alkalinity, and corals draw on both at the same time. Dosing one without the other lets the second parameter drift.

How is this different from Reef Complete?
Reef Complete is an all-in-one calcium supplement you can dose by itself. Reef Fusion 1 is the calcium part of a matched two-part system meant to be dosed with Reef Fusion 2 for tighter control in faster-growing tanks.

Will it change my pH?
Reef Fusion 1 is formulated to raise calcium without spiking pH. Dose gradually and test, especially in smaller water volumes.

Which size should I buy?
Nano and small reefs do well with the 500 mL or 1 L. Larger or SPS-heavy systems that dose daily get the best value from the 2 L or 4 L.