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Home » Saltwater Aquarium Supplies  » Additives & Supplements  » Magnesium & Iron  » Dry / Powder Supplements  »  Brightwell Aquatics Magnesion-P - Dry Magnesium Supplement for Reef Aquaria 300g / 10.6oz
Brightwell Aquatics Magnesion-P - Dry Magnesium Supplement for Reef Aquaria 300g / 10.6oz

Brightwell Aquatics Magnesion-P - Dry Magnesium Supplement for Reef Aquaria 300g / 10.6oz

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Brightwell Aquatics Magnesion-P - Dry Magnesium Supplement for Reef Aquaria 300g / 10.6oz Information

  • High-purity powdered magnesium blend.
  • Provides magnesium, which helps regulate the balance between calcium and carbonates in aquarium water, and is a component of aragonite, the mineral secreted by reef-building organisms to form skeletal material.
  • Stronger and more economical than liquid magnesium solutions; created for hobbyists maintaining multiple reef aquaria.
  • Formulated by a marine scientist.
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).

Instructions and Guidelines
Basic: Dissolve 2.5 grams (~½ teaspoon) of product per 20 US-gallons of aquarium water in 8-fl. oz. of fresh water; add 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, 1,200 g treats up to 9,600 US-gallons (36,340 L).
Advanced: Create a stock solution by dissolving 20 grams (~4 teaspoons) of Magnesion-P in 8-fl. oz. of fresh water (preferably purified); each ml of the solution will increase magnesium concentration (”[Mg2+]”) in 1 US-gallon (3.785 L) of water by 6.0 ppm. [Reference: Each g of Magnesion-P will increase the [Mg2+] in 1 US-gallon (3.785 L) of water by 114.4 ppm.] If initial [Mg2+] in the aquarium is below 1,288 ppm, add stock sol’n at maximum rate of 10 ml per 20 US-gallons daily until desired [Mg2+] is attained, then dose daily or weekly as needed (see below). Maintain [Mg2+] within a range of +/-10 ppm. Once desired [Mg2+] has been acquired, measure aquarium`s [Mg2+] at the same time each day over a one- to two-week period to determine the daily rate of magnesium uptake (i.e. the decrease in magnesium). To determine daily dosing rate (preferable to weekly dosing): estimate volume of water in entire aquarium system (US-gal.); divide the daily decrease in [Mg2+] by 6.0; multiply this number by volume of water in system to obtain daily ml of stock sol’n required to maintain stable [Mg2+].

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

Guaranteed Analysis (by weight)
Magnesium (min) 43% (430,000 ppm)
Magnesium sulfate (anhydrous), Magnesium chloride (anhydrous)

Reef Chemistry Calculator
Use our chemistry calculator to find out how much you need to add to your aquarium.

Manufacturer Info

Brightwell Aquatics Aquarium Supplies
The goal of Brightwell Aquatics is to provide the absolute highest quality, scientifically-sound products and customer service of any aquarium water care manufacturer, and to do it all in a straight-forward and honorable fashion. All Brightwell products are formulated by marine scientists with a passion for the aquarium hobby. They utilize the highest purity ingredients in concentrations that provide the most use to hobbyists. Nearly all Brightwell Aquatics products are over 99.9% pure. The usage guidelines of Brightwell Aquatics products are written in plain language but the company is always available to answer consumer questions. All products are lot numbered for quality control and customer service.

Brightwell Aquatics Magnesion-P - Dry Magnesium Supplement for Reef Aquaria 300g / 10.6oz Reviews

Average Rating
(6 reviews)
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Reviewers Rating Excellent!

Posted: 12/11/2013 from Los Altos, CA UNITED STATES
5.0 5
Experience Level: Expert

Comments: I prefer this dry product to the liquid form it used to come in, as it is more economical. It's easy to mix and does not have the precipitate that the liquid version had. I just wish they had a larger size container available.

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Reviewers Rating Great

Posted: 6/1/2011 from OH UNITED STATES
4.0 5
Experience Level: Intermediate

Comments: The product seems to work as advertised. I do like the fact that I dont have to use a ton of epsom salts as the product does contain chlorides as well. I use mainly for new saltwater augmentation.

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Dissolves fast, great results.

Reviewers Rating Excellent!

Posted: 6/28/2010 from PLYMOUTH, IN UNITED STATES
5.0 5
Experience Level: Expert

Comments: There is no more bang for your buck than this product. It is almost a powder and dissolves nearly instantly when added to RO water. Use caution however, if you add several tablespoons to a one cup measuring cup, the water will become hot enough to scald you. Best to mix with cold water. I mix up a batch and store it in a glass wine bottle for daily dosing. MUCH cheaper than liquid and a total no-brainer to use.

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Cost Effective

Reviewers Rating Excellent!

Posted: 12/9/2009 from ORLANDO, FL UNITED STATES
5.0 5
Experience Level: Intermediate

Comments: This is a more cost effective product than liquid products. Simply add the powder to RO/DI water and make the same solution sold in the bottle! This little canister will last a long time for my tank.

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Great Stuff

Reviewers Rating Excellent!

Posted: 11/23/2009 from MORENO VALLEY, CA UNITED STATE
5.0 5
Experience Level: Intermediate

Comments: My mg++ had fallen to 850 well below the desired 1350 I was looking for. I had been dosing with various liquid additives over the past month and was having very little success. My LFS recommended using this product so I gave it a try. I have been slowly dosing my 60 gal tank through the auto top off and after 3 weeks my mg++ is up to 1200 and rising. There are cheaper ways of dosing mg++ but I have been using Brightwell products for over a year and they have never cause me any problems, only helped.

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Great for raising magnesium

Reviewers Rating Excellent!

Posted: 12/9/2008 from CEDAR PARK, TX UNITED STATES
5.0 5
Experience Level: Expert

Comments: I tried a few other products to raise my magnesium from 900 to 1300. The others raised it by about 50 a week. This product will raise it by 50 a day if you want. Great for increasing magnesium in change water before you add it.

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