Magnesium¹²+
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Magnesium¹²+ is a concentrated magnesium supplement formulated for reef aquariums. It is intended for occasional correction when magnesium levels fall below the natural seawater range (1,280–1,350 ppm). Unlike daily maintenance formulas, Magnesium 12+ delivers magnesium alone, without additional trace ions, making it ideal for safely raising levels without disturbing balance. Each mL increases magnesium by 10 ppm per 1 US gallon (3.8 L).
Instructions
Test magnesium with a reliable kit before dosing.
Calculate dose: 1 mL per 1 US gallon = +10 ppm magnesium 1 mL per 10 US gallons = +1 ppm magnesium
Dose safely: Do not increase magnesium by more than 50–100 ppm per day. Add dose gradually into a high-flow sump or display area. Re-test magnesium after 12–24 hours before repeating.
Example: In a 100-gallon system, 500 mL (≈1 bottle) raises magnesium by ~+50 ppm.
Ingredients
- Purified RO/DI water
- USP-grade magnesium salts
Storage
- Store tightly sealed in a cool, shaded location (≤25 °C / 77 °F).
- Protect from direct light.
- Shelf life: 24 months.
- Crystals that may form below 10 °C will redissolve when warmed and shaken.
Safety Information
- Not for human consumption.
- Avoid contact with eyes, skin, and clothing.
- If on skin or in eyes, rinse with water for 15 minutes.
- If swallowed, rinse mouth and seek medical advice.
- Wash hands after use.
- Keep out of reach of children and pets.
- Discard according to local regulations.
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All orders are fulfilled directly by the individual brands, suppliers.
Additional shipping charges may apply to orders with more than one brand.
Canadian Owned Business
The business is majority or fully owned by Canadian citizens.

$16.99 CAD