Brightwell Aquatics

Magnesion - Liquid Magnesium Supplement - Brightwell Aquatics

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Magnesion - Liquid Magnesium Supplement for Reef Aquaria 250ml - Brightwell Aquatics

SKU: 209251

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Magnesion - Liquid Magnesium Supplement for Reef Aquaria 500ml - Brightwell Aquatics

SKU: 209252

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Magnesion - Liquid Magnesium Supplement for Reef Aquaria 2L- Brightwell Aquatics

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    Instructions and Guidelines

    Basic: Shake product well before using. Add 5 ml (1 capful) of product per 20 US-gallons of aquarium water every other day or as needed to maintain the magnesium concentration within a range of 1,290 - 1,320 ppm. When used in this fashion, 250 ml treats up to 1,000 US-gallons (3,785 L).

    Advanced: Determine the magnesium concentration in the aquarium using an accurate test kit before supplementing. Shake this product well before using. Each ml of Magnesion will increase the concentration of magnesium (“[Mg2+]”) in 1 US-gallon (3.785 L) of water by 26 ppm. If the initial [Mg2+] in the aquarium is below 1,288 ppm, add this product at the maximum rate of 10 ml per 20 US-gallons daily until the desired concentration is attained, then dose daily or weekly as needed (see below). Always try to maintain the [Mg2+] within a range of +/-10 ppm. To determine the dosing rate of this product once the desired [Mg2+] has been acquired, measure the daily rate of magnesium uptake (i.e. the decrease in magnesium) in your aquarium by measuring the aquarium's [Mg2+] at the same time each day over a one- to two-week period. To determine the daily dosing rate (preferable to weekly dosing) for magnesium maintenance: estimate the volume of water in the entire aquarium system; divide the daily decrease in [Mg2+] by 26; multiply this number by the volume of water in the system to get the daily dosage required (ml) to maintain a stable [Mg2+]. Daily dosing maintains a more stable [Mg2+] (and more natural environment) than dosing weekly, in which the [Mg2+] spikes just after dosing and then gradually decreases throughout the course of the week.


    Keep out of reach of children. Not for human consumption.


    Guaranteed Analysis

    Magnesium (min) 2,959 mg/oz. (100,000 ppm)

    Purified water, Magnesium sulfate, Magnesium chloride

    Technical Background

    Magnesium plays a vital role in reef aquaria: it helps maintain calcium and carbonate (composing the majority of measurable alkalinity) concentrations by limiting unwanted inorganic precipitation with each other. In the absence of adequate magnesium ions, calcium and carbonate ions bond rapidly, depleting their concentrations in the system and creating the false impression that heavier supplementation is required to re-establish the desired concentrations. No matter how much calcium is added, its natural seawater concentration of 412 ppm will never be sustained until the magnesium concentration begins to approach 1,290 ppm. Once the balance between calcium and magnesium has been established, subsequent calcium supplementation yields immediate positive results. Keeping magnesium within a range of 1,290-1,320 ppm will maintain the desired balance, and provides enough of the element to reef-building organisms for the formation of aragonite (~0.10% Mg by weight).

    The rate at which magnesium is extracted from the water is determined by the stocking density of reef-building livestock, type of lighting, and other conditions; therefore, each aquarium will have different requirements for the rate of magnesium supplementation. Once the rate of magnesium uptake in the aquarium has been determined, the proper dosing rate of this product can be easily calculated. It is recommended that a quality salt mix with the proper (not augmented) alkalinity and concentrations of major, minor, and trace elements be used to establish natural seawater parameters in the reef aquarium, providing a stable ionic foundation on which to build.

    All Brightwell Aquatics liquid water care supplements are made with purified water and high purity materials. We develop formulae for aquaria based on empirical data, using observation and measurement rather than theory.

    More Information
    Product Name Magnesion - Liquid Magnesium Supplement - Brightwell Aquatics
    SKU Magnesion-Liquid-Magnesium-Supplement-Brightwell-Aquatics
    Additive Type Magnesium
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