Brightwell Aquatics Reef Aquarium Calcium Supplement, 1L Reef Code A for Two-Part Dosing

Brightwell Aquatics Reef Code A is a 1L calcium supplement for reef aquariums, designed as the calcium component of a two-part dosing system used with equal parts Reef Code B.

• Matches natural seawater calcium ratios when paired with Reef Code B — supports balanced calcium and alkalinity dosing.
• Supplies calcium, magnesium, strontium, potassium, plus minor and trace minerals — supports corals, clams and calcareous algae.
• Contains no phosphate, silicate or organic material — keeps these ingredients out of the supplement.
• Made in the USA and formulated by a marine scientist — brings a science-led formulation to aquarium maintenance.
• Use in marine or freshwater aquariums — offers dosing versatility across aquatic setups.

Maintaining calcium and alkalinity is part of caring for reef-building organisms, including corals, clams and calcareous algae. Reef Code A is made for aquarium keepers who want a measured calcium supplement for a new setup or an established tank, with Reef Code B providing the corresponding carbonate component.

What does Reef Code A do for a reef aquarium?

Reef Code A supplies the calcium side of a two-part method for maintaining calcium and alkalinity. Used with equal parts Reef Code B, it is formulated to match natural seawater ratios and maintain ionic balance. Its mineral composition includes calcium, magnesium, strontium and potassium, along with minor and trace minerals. The brand also describes the formula as stronger than most competing products.

• Reef Code B supplies carbonates and other anions.
• The two-part method is intended to support reef-building organisms.

How do I dose Reef Code A?

Shake the bottle well and test calcium concentration before dosing. Add 5 ml (0.17 US fl oz) per 25 gallons (94.6 L) of aquarium water every other day, or as needed to sustain alkalinity within the stated range of 412 to 450 ppm. Use Reef Code A with equal parts Reef Code B.

• 250 ml (8.45 US fl oz) treats up to 1,250 gallons (4,731.8 L) when used as directed.
• Adjust dosing based on aquarium testing and the stated alkalinity range.

Which aquariums and organisms is it made for?

Reef Code A is intended for reef aquariums and is also presented for use in marine and freshwater aquariums. Its calcium and multi-mineral supplement supports reef-building organisms such as corals, clams and calcareous algae. It can be used when setting up a new aquarium or maintaining an established one.

• Made for aquarium water treatment, not as a standalone source of the carbonate component.
• Pair it with Reef Code B for the two-part approach to calcium and alkalinity dosing.

What is in the formula, and where is it made?

The formula contains major minerals including calcium, magnesium, strontium and potassium, plus minor and trace minerals. It contains no phosphate, silicate or organic material. Brightwell Aquatics Reef Code A is made in the USA and formulated by a marine scientist.

• Pack size: 1L.
• Designed to simplify calcium and alkalinity maintenance through a two-part dosing method.

Reef keepers maintaining calcium and alkalinity for corals, clams or calcareous algae can use Reef Code A as the calcium part of a paired dosing routine; aquarium keepers should follow the stated measurement and test calcium before dosing. Its defined role is calcium supplementation, with Reef Code B providing the matching carbonate component.