{"product_id":"brightwell-magnesion-500ml","title":"Brightwell Aquatics Magnesion 500 mL – Reef Aquarium Magnesium Supplement","description":"\u003cp\u003eBrightwell Aquatics Magnesion 500 mL is a highly concentrated ionic magnesium supplement formulated for marine and reef aquariums. It helps establish and maintain magnesium within the natural seawater range while supporting balanced calcium, alkalinity, and carbonate chemistry.\u003c\/p\u003e\n\u003cp\u003eMagnesium plays an important role in reef aquarium stability. Adequate magnesium helps reduce unwanted calcium-carbonate precipitation, allowing calcium and alkalinity to remain more readily available to corals, clams, coralline algae, and other reef-building organisms.\u003c\/p\u003e\n\u003cp\u003eMagnesion contains no unwanted organic complexing agents such as EDTA, gluconate, or polygluconate. Its concentrated liquid formula is easy to measure for routine maintenance or controlled correction of a tested magnesium deficiency.\u003c\/p\u003e\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eConcentrated Ionic Magnesium:\u003c\/strong\u003e Raises magnesium in marine and reef aquariums\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSupports Reef Chemistry:\u003c\/strong\u003e Helps regulate the balance between calcium and carbonates\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSupports Calcification:\u003c\/strong\u003e Magnesium is incorporated into aragonite produced by corals, clams, and other reef-building organisms\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHelps Limit Precipitation:\u003c\/strong\u003e Proper magnesium levels help keep calcium and carbonate available in aquarium water\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNo Organic Complexing Agents:\u003c\/strong\u003e Contains no EDTA, gluconate, or polygluconate\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest-Based Dosing:\u003c\/strong\u003e Suitable for routine maintenance and controlled magnesium correction\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMarine \u0026amp; Reef Formula:\u003c\/strong\u003e Intended for saltwater aquariums\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLarge 500 mL Size:\u003c\/strong\u003e Treats up to approximately 2,000 cumulative gallons at the basic dose\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eProduct Details\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand:\u003c\/strong\u003e Brightwell Aquatics\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct:\u003c\/strong\u003e Magnesion\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSize:\u003c\/strong\u003e 500 mL\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEquivalent Size:\u003c\/strong\u003e Approximately 16.9 fl oz\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eProduct Type:\u003c\/strong\u003e Ionic magnesium supplement\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAquarium Type:\u003c\/strong\u003e Marine and reef aquariums\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRecommended Magnesium Range:\u003c\/strong\u003e 1,290–1,320 ppm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBasic Dose:\u003c\/strong\u003e 5 mL per 20 US gallons every other day\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaximum Correction Dose:\u003c\/strong\u003e 10 mL per 20 US gallons daily\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eConcentration:\u003c\/strong\u003e 1 mL raises magnesium by approximately 26 ppm in 1 US gallon\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eBest Used For\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eReef aquariums with tested magnesium deficiencies\u003c\/li\u003e\n\u003cli\u003eSPS, LPS, soft-coral, and mixed reef systems\u003c\/li\u003e\n\u003cli\u003eMarine aquariums containing clams or coralline algae\u003c\/li\u003e\n\u003cli\u003eMaintaining magnesium near natural seawater levels\u003c\/li\u003e\n\u003cli\u003eSupporting calcium and alkalinity stability\u003c\/li\u003e\n\u003cli\u003eReplacing magnesium consumed between water changes\u003c\/li\u003e\n\u003cli\u003eCorrecting low magnesium gradually\u003c\/li\u003e\n\u003cli\u003eSystems using calcium and alkalinity supplements\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eWhy Magnesium Matters\u003c\/h3\u003e\n\u003cp\u003eMagnesium is one of the major ions found in seawater. It helps regulate interactions between calcium and carbonate and reduces the tendency of these ions to precipitate prematurely as calcium carbonate.\u003c\/p\u003e\n\u003cp\u003eWhen magnesium is too low, aquarists may have difficulty maintaining calcium and alkalinity even when those supplements are being added regularly. Correcting the magnesium deficiency may make the overall reef supplementation program easier to stabilize.\u003c\/p\u003e\n\u003cp\u003eMagnesium is also incorporated into aragonite, the mineral structure produced by stony corals, clams, coralline algae, and other calcifying marine organisms.\u003c\/p\u003e\n\u003ch3\u003eBasic Directions\u003c\/h3\u003e\n\u003cp\u003eShake the bottle well before each use.\u003c\/p\u003e\n\u003cp\u003eAdd:\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e5 mL per 20 US gallons every other day, or as needed to maintain magnesium between 1,290 and 1,320 ppm.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eTest magnesium regularly and adjust the frequency according to the aquarium’s actual rate of consumption.\u003c\/p\u003e\n\u003ch3\u003eBasic Dosage Guide\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e10 Gallons:\u003c\/strong\u003e Approximately 2.5 mL every other day\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e20 Gallons:\u003c\/strong\u003e 5 mL every other day\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e40 Gallons:\u003c\/strong\u003e 10 mL every other day\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e50 Gallons:\u003c\/strong\u003e Approximately 12.5 mL every other day\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e55 Gallons:\u003c\/strong\u003e Approximately 13.75 mL every other day\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e75 Gallons:\u003c\/strong\u003e Approximately 18.75 mL every other day\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e100 Gallons:\u003c\/strong\u003e 25 mL every other day\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e125 Gallons:\u003c\/strong\u003e Approximately 31.25 mL every other day\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e150 Gallons:\u003c\/strong\u003e Approximately 37.5 mL every other day\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e200 Gallons:\u003c\/strong\u003e 50 mL every other day\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThese amounts are the manufacturer’s basic maintenance doses. Do not dose automatically if magnesium is already within or above the desired range.\u003c\/p\u003e\n\u003ch3\u003eCorrecting Low Magnesium\u003c\/h3\u003e\n\u003cp\u003eDetermine the aquarium’s magnesium concentration with an accurate marine magnesium test before dosing.\u003c\/p\u003e\n\u003cp\u003eIf magnesium is below approximately 1,288 ppm, Magnesion may be added at a maximum rate of:\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e10 mL per 20 US gallons daily.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eContinue testing and stop corrective dosing when the desired concentration is reached. After correction, switch to a smaller daily or weekly maintenance amount based on the aquarium’s measured consumption.\u003c\/p\u003e\n\u003cp\u003eDo not exceed the maximum correction rate. Raising magnesium gradually reduces the risk of sudden changes in salinity and ionic balance.\u003c\/p\u003e\n\u003ch3\u003eAdvanced Dosing Formula\u003c\/h3\u003e\n\u003cp\u003eEach 1 mL of Magnesion raises magnesium by approximately 26 ppm in 1 US gallon of aquarium water.\u003c\/p\u003e\n\u003cp\u003eUse the following formula:\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eRequired mL = Aquarium gallons × desired magnesium increase ÷ 26\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch4\u003eExample\u003c\/h4\u003e\n\u003cp\u003eTo raise magnesium by 50 ppm in a 100-gallon system:\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003e100 × 50 ÷ 26 = approximately 192 mL total\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThis total amount should not be added all at once. The maximum daily dose for a 100-gallon aquarium is 50 mL, so the correction should be divided across several days while magnesium is tested regularly.\u003c\/p\u003e\n\u003ch3\u003eApproximate Dose Needed to Raise Magnesium by 10 ppm\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e20 Gallons:\u003c\/strong\u003e Approximately 7.7 mL\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e40 Gallons:\u003c\/strong\u003e Approximately 15.4 mL\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e50 Gallons:\u003c\/strong\u003e Approximately 19.2 mL\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e75 Gallons:\u003c\/strong\u003e Approximately 28.8 mL\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e100 Gallons:\u003c\/strong\u003e Approximately 38.5 mL\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e125 Gallons:\u003c\/strong\u003e Approximately 48.1 mL\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e150 Gallons:\u003c\/strong\u003e Approximately 57.7 mL\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e200 Gallons:\u003c\/strong\u003e Approximately 76.9 mL\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eCalculate dosage from the aquarium’s actual water volume after accounting for displacement from rock, sand, and equipment.\u003c\/p\u003e\n\u003ch3\u003eDetermining the Maintenance Dose\u003c\/h3\u003e\n\u003cp\u003eAfter reaching the desired magnesium level, measure magnesium at approximately the same time each day for one to two weeks.\u003c\/p\u003e\n\u003cp\u003eCalculate the average daily decrease, then use this formula:\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDaily dose in mL = Aquarium gallons × daily magnesium decrease ÷ 26\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eSmaller daily additions generally maintain a more stable magnesium concentration than occasional large corrections.\u003c\/p\u003e\n\u003ch3\u003eHow Much Does the 500 mL Bottle Treat?\u003c\/h3\u003e\n\u003cp\u003eAt the basic dosage of 5 mL per 20 gallons:\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eA 500 mL bottle provides approximately 100 standard doses and treats up to 2,000 cumulative gallons.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eExamples include:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eApproximately 100 basic doses for a 20-gallon aquarium\u003c\/li\u003e\n\u003cli\u003eApproximately 50 basic doses for a 40-gallon aquarium\u003c\/li\u003e\n\u003cli\u003eApproximately 20 basic doses for a 100-gallon aquarium\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eActual product life depends on aquarium size, starting magnesium concentration, water-change schedule, salt mix, and magnesium demand.\u003c\/p\u003e\n\u003ch3\u003eUsing Magnesion with Calcium and Alkalinity Supplements\u003c\/h3\u003e\n\u003cp\u003eMagnesion may be used as part of a reef supplementation program that also includes calcium and alkalinity products.\u003c\/p\u003e\n\u003cp\u003eTest each parameter separately because calcium, alkalinity, and magnesium are consumed at different rates. Do not assume equal amounts of all three supplements will be required.\u003c\/p\u003e\n\u003cp\u003eAdd concentrated supplements separately into an area of strong water movement. Do not mix Magnesion directly with calcium or alkalinity concentrates in the same dosing container unless the product manufacturer specifically allows it.\u003c\/p\u003e\n\u003ch3\u003eUsing Magnesion with Water Changes\u003c\/h3\u003e\n\u003cp\u003eA quality marine salt mix should establish magnesium near the desired seawater range. Test newly mixed saltwater before adding additional magnesium because salt mixes vary in concentration.\u003c\/p\u003e\n\u003cp\u003eRegular water changes may replace part or all of the magnesium consumed by lightly stocked systems. Heavily stocked reef aquariums may require additional supplementation between water changes.\u003c\/p\u003e\n\u003ch3\u003eMagnesion vs. Hydrāt-Mg\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMagnesion:\u003c\/strong\u003e Intended primarily to establish and maintain magnesium near the natural seawater range of 1,290–1,320 ppm\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHydrāt-Mg:\u003c\/strong\u003e A separate Brightwell formula that may be used by experienced aquarists when intentionally maintaining magnesium at substantially elevated concentrations\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eMost reef aquariums should maintain magnesium near the range recommended for Magnesion rather than intentionally raising it far above natural seawater levels.\u003c\/p\u003e\n\u003ch3\u003eDoes Magnesion Directly Grow Corals?\u003c\/h3\u003e\n\u003cp\u003eMagnesion supplies magnesium, an important component of stable reef chemistry and aragonite formation. However, it does not directly guarantee coral growth, coloration, or recovery.\u003c\/p\u003e\n\u003cp\u003eCoral growth also depends on:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eStable alkalinity\u003c\/li\u003e\n\u003cli\u003eAdequate calcium\u003c\/li\u003e\n\u003cli\u003eAppropriate lighting\u003c\/li\u003e\n\u003cli\u003eBalanced nitrate and phosphate\u003c\/li\u003e\n\u003cli\u003eSuitable water flow\u003c\/li\u003e\n\u003cli\u003eStable salinity and temperature\u003c\/li\u003e\n\u003cli\u003eFeeding and trace-element availability\u003c\/li\u003e\n\u003cli\u003eFreedom from pests and disease\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eImportant Testing Guidance\u003c\/h3\u003e\n\u003cp\u003eAlways test magnesium before attempting a correction. Unexpected results may come from an inaccurate test, incorrect saltwater volume, or errors in test procedure.\u003c\/p\u003e\n\u003cp\u003eFor reliable results:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eUse a quality marine magnesium test\u003c\/li\u003e\n\u003cli\u003eFollow the test instructions precisely\u003c\/li\u003e\n\u003cli\u003eConfirm unusual readings before adding a large dose\u003c\/li\u003e\n\u003cli\u003eCalculate from actual system water volume\u003c\/li\u003e\n\u003cli\u003eRetest during multi-day corrections\u003c\/li\u003e\n\u003cli\u003eMonitor calcium, alkalinity, and salinity alongside magnesium\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eCan Magnesion Be Overdosed?\u003c\/h3\u003e\n\u003cp\u003eYes. Excessive magnesium supplementation can disrupt the aquarium’s ionic balance and increase salinity.\u003c\/p\u003e\n\u003cp\u003eDo not add Magnesion simply because calcium or alkalinity is difficult to maintain. First confirm that magnesium is actually below the desired range.\u003c\/p\u003e\n\u003cp\u003eIf an excessive amount is added, stop dosing, verify magnesium and salinity, and perform gradual water changes with correctly mixed saltwater if necessary.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is Brightwell Magnesion used for?\u003c\/strong\u003e\u003cbr\u003eIt raises and maintains magnesium in marine and reef aquariums while supporting balanced calcium and carbonate chemistry.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat magnesium level does Brightwell recommend?\u003c\/strong\u003e\u003cbr\u003eBrightwell recommends maintaining magnesium between approximately 1,290 and 1,320 ppm.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the basic dose?\u003c\/strong\u003e\u003cbr\u003eAdd 5 mL per 20 gallons every other day or as needed based on testing.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow much does 1 mL raise magnesium?\u003c\/strong\u003e\u003cbr\u003eOne milliliter raises magnesium by approximately 26 ppm in 1 gallon of water.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the maximum daily correction dose?\u003c\/strong\u003e\u003cbr\u003eDo not exceed 10 mL per 20 gallons daily.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow much does the 500 mL bottle treat?\u003c\/strong\u003e\u003cbr\u003eAt the basic dose, it treats up to approximately 2,000 cumulative gallons.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhy is magnesium important in reef aquariums?\u003c\/strong\u003e\u003cbr\u003eMagnesium helps regulate calcium and carbonate interactions and reduces unwanted calcium-carbonate precipitation.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes Magnesion raise calcium or alkalinity?\u003c\/strong\u003e\u003cbr\u003eNo. It is a magnesium-specific supplement. Calcium and alkalinity should be tested and supplemented separately when required.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan it be used with calcium and alkalinity supplements?\u003c\/strong\u003e\u003cbr\u003eYes. Dose each product separately and adjust each one according to its respective test result.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs Magnesion reef safe?\u003c\/strong\u003e\u003cbr\u003eYes, when used as directed and dosed according to accurate magnesium testing.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill Magnesion prevent all calcium precipitation?\u003c\/strong\u003e\u003cbr\u003eNo. Proper magnesium helps reduce premature precipitation, but excessively high pH, calcium, or alkalinity can still cause calcium carbonate to precipitate.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes Magnesion contain EDTA?\u003c\/strong\u003e\u003cbr\u003eNo. Brightwell states that it contains no unwanted organic material such as EDTA, gluconate, or polygluconate.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I dose Magnesion automatically?\u003c\/strong\u003e\u003cbr\u003eYes, after determining the aquarium’s actual daily magnesium consumption and accurately calibrating the dosing pump.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs Magnesion suitable for freshwater aquariums?\u003c\/strong\u003e\u003cbr\u003eNo. It is formulated for marine and reef aquarium chemistry.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes Magnesion replace water changes?\u003c\/strong\u003e\u003cbr\u003eNo. It supplements magnesium but does not remove waste or replace routine aquarium maintenance.\u003c\/p\u003e\n\u003ch3\u003eAvailable at Tropical Treasures Wyo\u003c\/h3\u003e\n\u003cp\u003eBrightwell Aquatics Magnesion 500 mL provides concentrated ionic magnesium for maintaining stable reef aquarium chemistry near natural seawater levels.\u003c\/p\u003e\n\u003cp\u003eVisit Tropical Treasures Wyo in Cheyenne, Wyoming, to shop Brightwell Aquatics Magnesion, marine magnesium tests, calcium and alkalinity supplements, reef salt mixes, dosing equipment, and other saltwater aquarium supplies.\u003c\/p\u003e","brand":"Tropical Treasures Wyo LLC","offers":[{"title":"Default Title","offer_id":53005252985045,"sku":null,"price":13.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0670\/4545\/8133\/files\/BRI01038-2T.png?v=1785007994","url":"https:\/\/tropicaltreasureswyo.com\/products\/brightwell-magnesion-500ml","provider":"Tropical Treasures Wyo LLC","version":"1.0","type":"link"}