Red Sea Reef Foundation C - Magnesium (MG) (1000 ml) Liquid

Red Sea Reef Foundation C is a concentrated magnesium supplement from Red Sea's Reef Care Program. Magnesium works hand-in-hand with calcium and alkalinity to support healthy coral growth, stable calcification, and vibrant reef chemistry. Dosing Foundation C alongside A and B keeps the big three balanced so your corals can lay down skeleton without hitting chemistry roadblocks.

Looking for more reef chemistry? Browse our Water Treatments.

• Raises and maintains magnesium (Mg) in reef aquariums
• Blend of magnesium, chloride, and sulfate salts in their natural seawater ratio
• Part of the Red Sea Reef Foundation program (A, B, C)
• 100% reef safe when dosed according to test results
• 1000 ml bottle — great value for mid-to-large reef systems

How often should I dose Foundation C?
Test magnesium weekly with a reliable kit and dose as needed to keep Mg in the 1300–1400 ppm range. Refer to the Red Sea label for gallons-per-ml dosing math.

Do I need all three Foundation products?
Yes for an active reef. A (calcium), B (alkalinity), and C (magnesium) are designed to work together. Low magnesium makes it very difficult to hold calcium and alkalinity stable.

Is this reef safe?
Yes, at correct dosing. Always test before dosing — adding magnesium without a test result can cause swings that stress corals.