Seachem Reef Complete – Concentrated Ionic Calcium for Reef Aquariums

The Calcium Backbone of a Thriving Reef

Calcium is one of the most important building blocks of coral growth, yet it's constantly consumed — and letting it slip below natural seawater levels holds your whole reef back.

Reef Complete is a concentrated 160,000 mg/L blend of liquid ionic calcium that replicates the calcium levels of natural seawater. Unlike simple calcium chloride products, it's blended to a higher pH so harmful ammonia gases off into the air rather than the water column, and it includes magnesium and strontium in natural utilization ratios (100:5:0.1, Ca:Mg:Sr) — all at a higher concentration than competing supplements.

That kind of engineered blend is the signature of Seachem Laboratories, a chemistry-driven company founded in 1979 in Madison, Georgia, where products are developed in-house by chemists. Rather than a plain calcium chloride solution, Reef Complete is deliberately formulated — higher pH, natural utilization ratios, higher concentration — and it is built to serve as the calcium foundation of Seachem's coordinated reef system, working with the line's alkalinity, magnesium, trace-element, and coral-nutrition products to keep every parameter in balance.

1. Beginners: dose 1 capful (5 mL) per 80 L (20 US gallons) twice a week and check calcium every 2 weeks.
2. Advanced keepers: dose toward the optimal 380-420 mg/L, where each 5 mL/80 L raises calcium by about 10 mg/L.
3. Keep calcium and carbonate supplements on alternate days or at least 30 minutes apart.

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Why Seachem Reef Complete

• Foundational reef calcium: supplies liquid ionic calcium that replicates natural seawater levels, the core building block calcifying corals depend on.
• Higher concentration than rivals: a concentrated 160,000 mg/L (160,000 ppm) calcium, versus the nearest competitor's 110,000 ppm, so doses are small and efficient.
• Balanced, thoughtfully blended: includes magnesium and strontium in natural utilization ratios (100:5:0.1, Ca:Mg:Sr) and is blended to a higher pH so ammonia gases off into the air, not the water column.
• Part of Seachem's reef system: designed to be dosed alongside the line's carbonate/alkalinity, magnesium, and trace supplements — on alternate days or 30 minutes apart from carbonate additives.

Best For

Reef aquariums with actively calcifying inhabitants — SPS and LPS stony corals, clams, and coralline algae — where maintaining calcium at natural seawater levels is essential and where the keeper wants a concentrated, balanced calcium source.

FAQ

How do I know how much to dose? Test your calcium and dose toward the optimal 380-420 mg/L. Beginners can use 1 capful (5 mL) per 80 L (20 US gallons) twice a week and re-check every 2 weeks; each 5 mL/80 L raises calcium by about 10 mg/L. Do not exceed 12.5 mL/80 L per day.

Can I mix it with my alkalinity supplement? No. Do not directly mix Reef Complete with any carbonate supplement. Add calcium and carbonate additives on alternate days or at least 30 minutes apart to avoid depleting carbonate alkalinity.

Is it reef-safe? Yes. Reef Complete is a reef-formulated ionic calcium blend with magnesium and strontium in natural ratios, made for coral and invertebrate aquariums.

What It Does

A concentrated (160,000 mg/L) optimized blend of liquid ionic calcium designed to replicate the calcium levels found in natural seawater. It also includes magnesium and strontium in amounts proportionate to typical utilization ratios (100:5:0.1, Ca:Mg:Sr), letting aquarists maintain these critical elements while holding optimal calcium levels. This formula is blended rather than simply composed of calcium chloride, and is blended to a higher pH to ensure harmful ammonia gases off into the atmosphere rather than the water column. It contains 160,000 ppm calcium, where the nearest competitor's product is only 110,000 ppm.

Directions

Beginner: Use 1 capful (5 mL) per 80 L (20 US gallons) of aquarium water twice a week. To be safe, check on the calcium levels every 2 weeks and carefully adjust the amount or the frequency of doses according to the specific needs of your aquarium. Advanced: Check on the calcium levels and then follow addition regimen until the calcium levels are adjusted to an optimal 380-420 mg/L. Each 5 mL/80 L (20 US gallons) will raise the calcium value by approximately 10 mg/L. The quantity or frequency can be adjusted, but be sure not to exceed 12.5 mL/80 L (20 US gallons) per day. Use as required to maintain ideal levels of calcium. Expert: After figuring out the calcium consumption rate of the aquarium, install a continuous drip system for easier dosing practices. Use the following formula to determine how much to add to your top-off water: m=vc/160 (m=mL of product to add to top-off water, v=volume of tank in liters, c=amount to raise calcium in mg/L). [For reference: 1 US gallon=3.8 L]. Do Not Overdose: The presence of excess calcium may contribute to the increased depletion of carbonate alkalinity. Do not directly mix Seachem Reef Complete with any carbonate supplement, and it is highly recommended that calcium and carbonate additives are added on alternate days or at least 30 minutes apart.

Available Sizes

500 mL