Red Sea Foundation C Magnesium Powder 1 KG (2.2lb)

Magnesium supplement for balanced formation of coral skeleton

It's all in the balance. Calcium, Magnesium, Strontium, and Carbonate are the basic foundation elements of coral skeletons. All of these elements need to be available in balanced proportions for positive coral growth — and Magnesium is the one most reefers forget until corals stop growing.

Red Sea Foundation C is a concentrated magnesium powder (Mg + minor and trace elements) designed to be dosed alongside Foundation A (Calcium) and Foundation B (Alkalinity) to maintain natural seawater ionic balance in any reef tank. Browse the full reef additives and saltwater supplies lineup.

Why Magnesium Matters

• Stops calcium/alkalinity precipitation — at low Mg levels, Ca and Alk react and crash. Holding Mg at ~1300 ppm keeps the foundation elements stable.
• Required for coralline growth — coralline algae uses magnesium for its skeleton just like SPS corals do.
• Trace blend included — Foundation C is more than just MgCl₂; it includes minor and trace elements found in natural seawater.
• Pairs with A & B — completes the Red Sea Foundation Program (A=Ca, B=Alk, C=Mg).

How to Use

1. Test first — measure your current Mg with a reliable reef test kit. Target: 1280–1340 ppm. Don't dose blindly.
2. Dissolve in RO/DI water — mix 1 KG of Foundation C into roughly 5 L of RO/DI water (per Red Sea instructions; refer to the label for exact dosing per ppm raise).
3. Dose slowly — never raise Mg by more than ~100 ppm per day. Sudden swings stress corals.
4. Maintain with regular testing — recheck weekly. SPS-heavy tanks typically need ongoing Mg dosing as corals deplete the supply.

Specifications

The Red Sea Foundation Program

• Foundation A — Calcium Powder 1 KG
• Foundation B — Alkalinity Powder 1 KG
• Foundation C — Magnesium Powder 1 KG (this product)
• Foundation Pro Multi Test Kit (Ca, Alk, Mg) — test all three with one kit

Recommended Pairings

• Aquaforest AF Magnesium Test Kit — alternative Mg test
• All water testing kits
• All aquarium additives & supplements
• Salt mixes

FAQ

How much does 1 KG raise Mg?
A 1 KG bag dissolved in 5 L of RO/DI water yields a concentrated stock solution. Refer to the label for exact dose-per-ppm-raise calculations based on your tank volume. As a rough rule, the bag will treat hundreds of gallons of tank water over time.

Can I dose this dry?
No — always dissolve in RO/DI water first. Dosing the powder directly can crash local water chemistry and stress nearby corals.

How often should I test Mg?
Weekly is standard for established reef tanks. Test more often if you've recently corrected a low Mg reading or added significant SPS coral.

Is it reef safe?
Yes — Foundation C is formulated specifically for marine reef aquariums when dosed at the recommended rate.