You are here: Home > ADDITIVES > Aquarium Additives by Type:
Calcium / Kalkwasser

Aquarium Calcium & Aquarium Kalkwasser Additives
Aquarium Kalkwasser
Aquarium Kalkwasser is the German term for a saturated solution of calcium hydroxide in water. Kalkwasser replenishes the calcium used during the growth of stony corals, coralline algae, clams, etc. Other benefits of kalkwasser include the precipitation of phosphate, maintenance of pH and alkalinity, and enhanced protein skimming. Aquarium kalkwasser can either be introduced into the tank or sump using a Kalkwasser Dosing system.

Aquarium Calcium
It is necessary to add aquarium calcium to reef aquariums in order to replenish the calcium utilized in the growth of soft and stony corals, pink coralline algae, calcareous algae, tridacna clams, and other invertebrates found in captive marine systems. Calcium can be added directly to the tank/sump. Aquarium calcium can also be introduced using a Calcium Reactor (which uses a different media than the calcium offered in this section).
Sort By:
Page of 3
Brightwell Aquatics Calcion Liquid Calcium Supplement, 2 liters
Brightwell Aquatics Calcion Liquid Calcium Supplement, 2 liters
Our Price: $31.00
In Stock

  • Highly-concentrated ionic calcium solution
  • Increases the concentration of calcium in marine aquarium water to provide corals and other reef-building invertebrates with one of the most important elements required for growth
  • Is ionic rather than chelated, and contains no unwanted organic material such as EDTA, gluconate, or polygluconate
  • Over 50% stronger than most competing products
  • Free of phosphate, silicate, and organic material
  • Formulated by a marine scientist
Brightwell Aquatics Calcion Liquid Calcium Supplement, 250 ml
Brightwell Aquatics Calcion Liquid Calcium Supplement, 250 ml
Our Price: $6.30
In Stock

  • Highly-concentrated ionic calcium solution
  • Increases the concentration of calcium in marine aquarium water to provide corals and other reef-building invertebrates with one of the most important elements required for growth
  • Is ionic rather than chelated, and contains no unwanted organic material such as EDTA, gluconate, or polygluconate
  • Over 50% stronger than most competing products
  • Free of phosphate, silicate, and organic material
  • Formulated by a marine scientist
Brightwell Aquatics Calcion Liquid Calcium Supplement, 500 ml
Brightwell Aquatics Calcion Liquid Calcium Supplement, 500 ml
Our Price: $10.90
In Stock

  • Highly-concentrated ionic calcium solution
  • Increases the concentration of calcium in marine aquarium water to provide corals and other reef-building invertebrates with one of the most important elements required for growth
  • Is ionic rather than chelated, and contains no unwanted organic material such as EDTA, gluconate, or polygluconate
  • Over 50% stronger than most competing products
  • Free of phosphate, silicate, and organic material
  • Formulated by a marine scientist
Brightwell Aquatics Calcion-P Dry Calcium Supplement, 200 grams
Brightwell Aquatics Calcion-P Dry Calcium Supplement, 200 grams
Our Price: $8.80
(Out of Stock)

  • High-purity powdered calcium
  • Increases the concentration of calcium in marine aquarium
    water to provide corals and other reef-building invertebrates
    with one of the most important elements required for growth
  • Stronger and more economical than liquid calcium solutions;
    created for hobbyists maintaining multiple reef aquaria
  • Formulated by a marine scientist
Brightwell Aquatics Calcion-P Dry Calcium Supplement, 400 grams
Brightwell Aquatics Calcion-P Dry Calcium Supplement, 400 grams
Our Price: $13.70
In Stock

  • High-purity powdered calcium
  • Increases the concentration of calcium in marine aquarium
    water to provide corals and other reef-building invertebrates
    with one of the most important elements required for growth
  • Stronger and more economical than liquid calcium solutions;
    created for hobbyists maintaining multiple reef aquaria
  • Formulated by a marine scientist
Brightwell Aquatics Calcion-P Dry Calcium Supplement, 800 grams
Brightwell Aquatics Calcion-P Dry Calcium Supplement, 800 grams
Our Price: $18.00
In Stock

  • High-purity powdered calcium
  • Increases the concentration of calcium in marine aquarium
    water to provide corals and other reef-building invertebrates
    with one of the most important elements required for growth
  • Stronger and more economical than liquid calcium solutions;
    created for hobbyists maintaining multiple reef aquaria
  • Formulated by a marine scientist
Brightwell Aquatics CoraLazarus High-Purity Calcium Media, 1000 grams
Brightwell Aquatics CoraLazarus High-Purity Calcium Media, 1000 grams
Our Price: $8.00
In Stock


  • High-purity natural mineral that may be employed in traditional calcium reactors, or even blended in to pre-existing aquarium substrate, to gradually increase and maintain the calcium concentration and alkalinity in marine aquaria
  • Strong source of calcium, the most abundant cation by percent mass in aragonite, the mineral secreted by reef-building organisms to form skeletal material
  • Through dissolution, provides calcium, magnesium, strontium, potassium, and carbonates
  • Aids in increasing alkalinity to stabilize pH and encourage rapid biogenic aragonite formation
  • Optimal average particle size for use in media reactors and calcium reactors
  • Free of chloride and sulphate
Brightwell Aquatics CoraLazarus High-Purity Calcium Media, 5 Kg
Brightwell Aquatics CoraLazarus High-Purity Calcium Media, 5 Kg
Our Price: $30.90
In Stock


  • High-purity natural mineral that may be employed in traditional calcium reactors, or even blended in to pre-existing aquarium substrate, to gradually increase and maintain the calcium concentration and alkalinity in marine aquaria
  • Strong source of calcium, the most abundant cation by percent mass in aragonite, the mineral secreted by reef-building organisms to form skeletal material
  • Through dissolution, provides calcium, magnesium, strontium, potassium, and carbonates
  • Aids in increasing alkalinity to stabilize pH and encourage rapid biogenic aragonite formation
  • Optimal average particle size for use in media reactors and calcium reactors
  • Free of chloride and sulphate
Brightwell Aquatics Kalk+2 Kalkwasser Supplement, 1.8 KG (4 lbs)
Brightwell Aquatics Kalk+2 Kalkwasser Supplement, 1.8 KG (4 lbs)
Our Price: $48.80
In Stock


  • Contains calcium, strontium, and magnesium in the same ionic ratios found in aragonite. This unique feature increases the usefulness of Kalk+2 to reef-building invertebrates such as corals, clams, calcareous algae, etc
  • Provides temporary alkalinity and helps maintain pH within the desired range when used as directed
  • Adds no conservative elements, such as chloride, to the aquarium
  • Improves upon the industry-standard powdered calcium supplement over the past three decades
  • Formulated by a marine scientist
Brightwell Aquatics Kalk+2 Kalkwasser Supplement, 100 grams
Brightwell Aquatics Kalk+2 Kalkwasser Supplement, 100 grams
Our Price: $7.00
In Stock

  • Contains calcium, strontium, and magnesium in the same ionic
    ratios found in aragonite. This unique feature increases the
    usefulness of Kalk+2 to reef-building invertebrates such as corals, clams, calcareous algae, etc
  • Provides temporary alkalinity and helps maintain pH within the
    desired range when used as directed
  • Adds no conservative elements, such as chloride, to the
    aquarium
  • Improves upon the industry-standard powdered calcium
    supplement over the past three decades
  • Formulated by a marine scientist
Brightwell Aquatics Kalk+2 Kalkwasser Supplement, 225 grams
Brightwell Aquatics Kalk+2 Kalkwasser Supplement, 225 grams
Our Price: $10.30
In Stock

  • Contains calcium, strontium, and magnesium in the same ionic
    ratios found in aragonite. This unique feature increases the
    usefulness of Kalk+2 to reef-building invertebrates such as corals, clams, calcareous algae, etc
  • Provides temporary alkalinity and helps maintain pH within the
    desired range when used as directed
  • Adds no conservative elements, such as chloride, to the
    aquarium
  • Improves upon the industry-standard powdered calcium
    supplement over the past three decades
  • Formulated by a marine scientist
Brightwell Aquatics Kalk+2 Kalkwasser Supplement, 450 grams
Brightwell Aquatics Kalk+2 Kalkwasser Supplement, 450 grams
Our Price: $14.20
In Stock

  • Contains calcium, strontium, and magnesium in the same ionic
    ratios found in aragonite. This unique feature increases the
    usefulness of Kalk+2 to reef-building invertebrates such as corals, clams, calcareous algae, etc
  • Provides temporary alkalinity and helps maintain pH within the
    desired range when used as directed
  • Adds no conservative elements, such as chloride, to the
    aquarium
  • Improves upon the industry-standard powdered calcium
    supplement over the past three decades
  • Formulated by a marine scientist
Brightwell Aquatics Liquid Reef, 2 L
Brightwell Aquatics Liquid Reef, 2 L
Our Price: $38.80
In Stock

  • Complete source of the elements and molecules that are directly used by corals, clams, and other reef-building invertebrates and organisms to create skeletal material and grow
  • Provides calcium (140,000 ppm), strontium, magnesium, and potassium in approximately the same ratios* in which they occur in aragonite
  • Very strong source of carbonates (derived from aragonite), the other important group of ions involved in aragonite formation
  • Increases alkalinity to help stabilize pH
  • Stronger than competing products
  • May be used as an inexpensive alternative to automated calcium reactor systems with similar results
  • Free of phosphate, silicate, and organic material
  • Formulated by a marine scientist
  • Basic Instructions: Shake product well before using. Add 5 ml (1 capful) of product per 50 US-gallons of aquarium water every other day or as needed to maintain the calcium concentration within a range of 412 - 450 ppm. When used in this fashion, 250 ml treats up to 2,500 US-gallons (9,464 L). Liquid Reef may temporarily cloud aquarium water after addition, therefore it is recommended that the product be dosed at night.
Brightwell Aquatics Liquid Reef, 250 ml
Brightwell Aquatics Liquid Reef, 250 ml
Our Price: $9.70
In Stock

  • Complete source of the elements and molecules that are directly used by corals, clams, and other reef-building invertebrates and organisms to create skeletal material and grow
  • Provides calcium (140,000 ppm), strontium, magnesium, and potassium in approximately the same ratios* in which they occur in aragonite
  • Very strong source of carbonates (derived from aragonite), the other important group of ions involved in aragonite formation
  • Increases alkalinity to help stabilize pH
  • Stronger than competing products
  • May be used as an inexpensive alternative to automated calcium reactor systems with similar results
  • Free of phosphate, silicate, and organic material
  • Formulated by a marine scientist
  • Basic Instructions: Shake product well before using. Add 5 ml (1 capful) of product per 50 US-gallons of aquarium water every other day or as needed to maintain the calcium concentration within a range of 412 - 450 ppm. When used in this fashion, 250 ml treats up to 2,500 US-gallons (9,464 L). Liquid Reef may temporarily cloud aquarium water after addition, therefore it is recommended that the product be dosed at night.
Brightwell Aquatics Liquid Reef, 500 ml
Brightwell Aquatics Liquid Reef, 500 ml
Our Price: $15.60
In Stock

  • Complete source of the elements and molecules that are directly used by corals, clams, and other reef-building invertebrates and organisms to create skeletal material and grow
  • Provides calcium (140,000 ppm), strontium, magnesium, and potassium in approximately the same ratios* in which they occur in aragonite
  • Very strong source of carbonates (derived from aragonite), the other important group of ions involved in aragonite formation
  • Increases alkalinity to help stabilize pH
  • Stronger than competing products
  • May be used as an inexpensive alternative to automated calcium reactor systems with similar results
  • Free of phosphate, silicate, and organic material
  • Formulated by a marine scientist
  • Basic Instructions: Shake product well before using. Add 5 ml (1 capful) of product per 50 US-gallons of aquarium water every other day or as needed to maintain the calcium concentration within a range of 412 - 450 ppm. When used in this fashion, 250 ml treats up to 2,500 US-gallons (9,464 L). Liquid Reef may temporarily cloud aquarium water after addition, therefore it is recommended that the product be dosed at night.
Brightwell Aquatics Reef Code Part A 2 Liter
Brightwell Aquatics Reef Code Part A, 2 Liter
Our Price: $14.10
In Stock

  • Reef Code A is the calcium-bearing component of a two-part method for dosing calcium and carbonates (the substances largely responsible for increasing alkalinity (”buffering capacity”)) in the same ratio as that found in natural seawater
  • Reef Code A is Ionically-balanced with respect to natural seawater concentrations of calcium and carbonates when used in equal amounts with Reef Code B
  • Benefits reef-building organisms such as corals, clams, calcareous algae, etc.
  • Simplifies calcium and alkalinity maintenance
  • Stronger than most competing products
  • Contains no phosphate, silicate, or organic material
  • Formulated by a marine scientist
  • Basic Instructions: Shake product well before using. Add 5 ml (1 capful) of product per 25 US-gallons of aquarium water every other day or as needed to maintain the calcium concentration within a range of 412 - 450 ppm. When used in this fashion, 250 ml treats up to 1,250 US-gallons (4,732 L). When used in equal amounts with Reef Cōde B, the calcium and carbonates being added are in the same ratio found in natural seawater. Do not mix products in the same container; this will cause the active components to precipitate and become ineffective. Allow 60 seconds to pass between dosing Reef Code A and B.
Brightwell Aquatics Reef Code Part A 500 ml
Brightwell Aquatics Reef Code Part A, 500 ml
Our Price: $7.60
In Stock

  • Reef Code Part A is the calcium-bearing component of a two-part method for dosing calcium and carbonates (the substances largely responsible for increasing alkalinity (”buffering capacity”)) in the same ratio as that found in natural seawater
  • Reef Code A is ionically-balanced with respect to natural seawater concentrations of calcium and carbonates when used in equal amounts with Reef Cōde B
  • Benefits reef-building organisms such as corals, clams, calcareous algae, etc.
  • Simplifies calcium and alkalinity maintenance
  • Stronger than most competing products
  • Contains no phosphate, silicate, or organic material
  • Formulated by a marine scientist
  • Basic Instructions: Shake product well before using. Add 5 ml (1 capful) of product per 25 US-gallons of aquarium water every other day or as needed to maintain the calcium concentration within a range of 412 - 450 ppm. When used in this fashion, 250 ml treats up to 1,250 US-gallons (4,732 L). When used in equal amounts with Reef Cōde B, the calcium and carbonates being added are in the same ratio found in natural seawater. Do not mix products in the same container; this will cause the active components to precipitate and become ineffective. Allow 60 seconds to pass between dosing Reef Cōde A and B.
Brightwell Aquatics Reef Code Part B, 2 liter
Brightwell Aquatics Reef Code Part B, 2 liter
Our Price: $14.10
In Stock

  • The carbonate-bearing component of a two-part method for dosing calcium and carbonates (the substances largely responsible for increasing alkalinity (”buffering capacity”)) in the same ratio as that found in natural seawater
  • Ionically-balanced with respect to natural seawater concentrations of calcium and carbonates when used in equal amounts with Reef Cōde A
  • Benefits reef-building organisms such as corals, clams, calcareous algae, etc.
  • Simplifies calcium and alkalinity maintenance
  • Stronger than most competing products
  • Contains no phosphate, silicate, or organic material
  • Formulated by a marine scientist
Brightwell Aquatics Reef Code Part B, 500 ml
Brightwell Aquatics Reef Code Part B, 500 ml
Our Price: $7.60
In Stock

  • The carbonate-bearing component of a two-part method for dosing calcium and carbonates (the substances largely responsible for increasing alkalinity (”buffering capacity”)) in the same ratio as that found in natural seawater
  • Ionically-balanced with respect to natural seawater concentrations of calcium and carbonates when used in equal amounts with Reef Cōde A
  • Benefits reef-building organisms such as corals, clams, calcareous algae, etc.
  • Simplifies calcium and alkalinity maintenance
  • Stronger than most competing products
  • Contains no phosphate, silicate, or organic material
  • Formulated by a marine scientist
E.S.V. 32 oz B-Ionic Calcium Buffer System
E.S.V. B-Ionic Calcium Buffer System 32 oz
Our Price: $13.99
(Out of Stock)

The E.S.V. B-Ionic Calcium Buffer is the original, unique, easy to use, two-component liquid supplement system. When using equal volumes of each component, the aquarist can easily maintain calcium and alkalinity levels with no mixing of powders, disruption of ionic balance, or addition of organic chemicals. In addition to supplying highly concentrated calcium and carbonate alkalinity required for calcification, B-Ionic Calcium Buffer System also provides all other important major, minor, and trace elements in the proper ratios to duplicate the composition of synthetic seawater. As a result, the B-Ionic Calcium Buffer System will help restore inorganic ions lost from protein skimming and help maintain the ionic balance of the aquarium water.