Calcium & Magnesium Test Kit

Measure calcium and magnesium with one organized titration kit built for saltwater and reef aquariums. Clear color-change endpoints, quick-read scales and formulas printed on the reusable stand make both tests easy to follow.

Video tutorial

What’s included

• 118 mL Calcium Buffer
• 20 g Calcium Indicator powder
• 118 mL Calcium Titrant
• 59 mL (2 oz) Magnesium Buffer A
• 7.5 mL Magnesium Indicator B
• 118 mL (4 oz) Magnesium Titrant C
• Sample vial, measuring and titration syringes, indicator scoop and reusable testing stand

How to test calcium

1. Add 5.00 mL of aquarium water to the sample vial.
2. Add 1.00 mL of Calcium Buffer.
3. Add one level scoop of Calcium Indicator and swirl to pink-orange.
4. Fill the Calcium Titrant syringe to 1.00 mL.
5. Add titrant slowly while swirling; stop at the first stable purple endpoint.
6. Calculate ppm Ca = mL of Calcium Titrant used × 600.

How to test magnesium

1. Add 5.00 mL of aquarium water to the sample vial.
2. Add 0.50 mL of Magnesium Buffer A.
3. Add 2 drops of Magnesium Indicator B and swirl to wine-red.
4. Fill the Magnesium Titrant C syringe to 1.00 mL.
5. Add titrant slowly while swirling; stop at a pure blue endpoint.
6. Record the titrant used and calculate ppm Mg = 1944.40 × mL MG-C − 363.87 × mL CA-C.

The case includes quick-read guidance for typical reef ranges of 400–600 ppm calcium and 1200–1500 ppm magnesium.

Already have the tools? Choose the Calcium & Magnesium Refill Reagents for the best refill value. Need only one component? Individual Calcium Buffer, Calcium Indicator, Calcium Titrant, Magnesium Buffer A, Magnesium Indicator B and Magnesium Titrant C are available separately.

Warning: Calcium Buffer contains 4% sodium hydroxide. Read every product label and SDS, wear suitable eye and hand protection, and keep out of reach of children.