Red Sea Reef Care Magnesium Foundation C (Powder)

• Mixes to full liquid strength – 1 mL of mixed stock raises 100 L by 1 ppm Mg, same as the ready-to-use liquid.
• Same magnesium salt blend as the liquid, balanced to natural seawater ratios.
• Space-efficient – a 1 kg tub replaces a large volume of pre-mixed liquid on the shelf.
• Bulk option – the 18 kg pail suits larger systems and multi-tank dosing stations.

Dissolve the full tub into the stated volume of RO/DI water – 1 kg into 1.67 L for the standard tub, scaled up to roughly 30 L for the 18 kg pail. The result mixes to the same strength as the ready-to-use liquid: dose 1 mL of stock per 100 L of tank water for every 1 ppm you need to raise magnesium, correcting gradually over several days for anything larger than about 20 ppm.

Why does this mix so much stronger than Foundation B powder?

Each element mixes to its own ratio. Foundation C dissolves to the same strength as the liquid; Foundation B is diluted further and doses at 3 mL per 100 L instead of 1 mL. Follow the ratio on the tub you have rather than assuming they match.

A 1 kg tub mixes to enough stock to raise 167,000 L of tank water by 1 ppm. The 18 kg pail raises just over 3,000,000 L by the same 1 ppm.

Suitable for marine and reef aquariums running calcium and alkalinity dosing, particularly larger systems where mixing your own magnesium stock is worth the saving over pre-mixed liquid. Not suitable if you don't have RO/DI water and a mixing container on hand – buy the ready-to-use liquid instead. Not intended for freshwater aquariums.

Keep out of reach of children and pets. Avoid inhaling the dry powder when mixing; avoid prolonged skin and eye contact. Store the sealed tub away from moisture. Safe for fish, coral and invertebrates once mixed and dosed at the recommended rate.

• Red Sea Reef Care KH/Alkalinity Foundation B (Powder) – the matching alkalinity element in dry format.
• Red Sea Reef Care Calcium+ Foundation A – dose alongside so calcium tracks magnesium and alkalinity.
• Red Sea Reef Foundation Pro Multi Testing Kit – test Mg before you dose, not after.
• Red Sea Reef Care Magnesium Foundation C – the ready-to-use liquid, for smaller tanks or when mixing isn't worth the saving.

Covered by the manufacturer's standard consumer guarantees in addition to your rights under Australian Consumer Law. The 18 kg pail ships on a pallet-rated carton – check delivery access for larger vehicles if you're off the beaten track.

Do I need RO/DI water to mix this?

Yes – tap water can introduce phosphate, silicate or metals that dosing pure magnesium salts is meant to avoid.

Is the 18 kg pail worth it over the 1 kg tub?

It only pays off if you have the dosing volume and storage to use it.

Can I dose the mixed stock through a dosing pump?

Yes – once mixed it doses exactly like the liquid, at 1 mL of stock per 100 L per 1 ppm.

How long does the mixed stock keep?

Store it sealed and out of direct sunlight, and use it within a few months for best results, as with any reef dosing solution.