Magnesium is easily one of the most overlooked elements in a saltwater aquarium and is an essential part of being able to hold calcium and alkalinity at the levels they need to be at for coral growth.

Pharma Magnesium Mix for General Adjustments by Bulk Reef Supply
Magnesium Additive

Pharma Magnesium for General Adjustments 1 Gallon Mix

Designed for larger magnesium corrections and alongside calcium reactors or kalkwasser. This balanced formula raises magnesium without disrupting calcium and alkalinity levels in a reef tank. Made with Pharmaceutical grade materials and product mixes fast & clear with no visible impurities.

1 Gallon Mix Ratio: 7 1/4 c. Magnesium Chloride : 1/2 c. Magnesium Sulfate
Best For: Larger corrections, kalkwasser users, and calcium reactor systems

Shop General Adjustments
Pharma Magnesium Mix for 2-Part Maintenance by Bulk Reef Supply
Magnesium Additive

Pharma Magnesium for 2-Part Maintenance 1 Gallon Mix

Built for ongoing, daily magnesium replenishment. This solution is a appropriate for use with BRS Pharma 2-part Solution for daily replenishment of calcium and alkalinity. Made with Pharmaceutical grade materials and product mixes fast & clear with no visible impurities.

1 Gallon Mix Ratio: 5 1/4 c. Magnesium Chloride : 2 c. Magnesium Sulfate
Best For: Routine magnesium maintenance with 2-part dosing systems

Shop 2-Part Maintenance

General Adjustments

Makes 1 gallon of liquid magnesium solution for larger corrections. Best for one-time magnesium adjustments or aquariums using kalkwasser or a calcium reactor.

  1. Using a clean 1-gallon jug or container, fill it halfway with RO/DI water.
  2. Add the appropriate BRS Pharma Magnesium
    1. If using the 1 gallon mix, add all of the pre-mixed dry material.
    2. If mixing larger quantities add 7 1/4 cups BRS Pharma Magnesium Chloride and 1/2 cup BRS Pharma Magnesium Sulfate per gallon of RO/DI water.
  3. Secure the cap and shake for about 10 seconds to begin dissolving the salts.
  4. Remove the cap and fill the container the rest of the way with RO/DI water.
  5. Replace the cap, shake again, and allow the salts to fully dissolve. This typically takes a couple of hours.

2-Part Maintenance

Makes 1 gallon of liquid magnesium solution for ongoing magnesium maintenance. Ideal for routine dosing or small weekly adjustments when using a 2-part dosing system.

  1. Using a clean 1-gallon jug or container, fill it halfway with RO/DI water.
  2. Add the appropriate BRS Pharma Magnesium
    1. If using the 1 gallon mix, add all of the pre-mixed dry material.
    2. If mixing larger quantities add 5 1/4 cups BRS Pharma Magnesium Chloride and 2 cups BRS Pharma Magnesium Sulfate per gallon of RO/DI water.
  3. Secure the cap and shake for about 10 seconds to begin dissolving the salts.
  4. Remove the cap and fill the container the rest of the way with RO/DI water.
  5. Replace the cap, shake again, and allow the salts to fully dissolve. This typically takes a couple of hours.

Magnesium Dosing Instructions

Dosing any magnesium solution takes a little math to avoid overdosing, but the process is made much easier with the BRS Reef Calculator. When adding any magnesium solution, dose it slowly into a high-flow area of the aquarium and monitor salinity during and after dosing.

Use the BRS Reef Calculator
  1. Mix your 1-gallon magnesium solution using the instructions above, then test your aquarium’s current magnesium level with your preferred test kit. Log the results.
  2. Go to the Magnesium Reef Calculator and choose Liquid Magnesium Mix for the product option.

    3. One Time Correction

  3. Enter your total system water volume, including the display and sump, minus displacement from rock or equipment, then click calculate. If you are unsure, using the display tank’s total water volume is a safe starting point.
  4. Enter your current magnesium levels and desired magnesium levels in the calculator and the calculator will provide your amount of liquid solution required to correct magnesium levels.
  5. Dose the calculated amount slowly into a high-flow area to raise magnesium to your desired level. This gives you your baseline and completes the one-time adjustment phase.

    6. Daily Dosage

  6. Test your magnesium levels and log the results. Ideally magnesium levels are within your desired range but if they are low, adjust first using above Process. Wait 5 days without dosing any magnesium, then retest magnesium at the same time of day you tested the first time to see how much the magnesium levels have changed over a 5 day period. Log the results.
  7. To determine your daily dose, go to the Magnesium Reef Calculator and choose Liquid Magnesium Mix for the product option, enter your total system water volume, current magnesium level and desired (current) magnesium level.
  8. The calculator will provide the amount of solution for the entire 5 day period. Simply divide the resulting dosage by 5 (since you waited 5 days) and that is how much magnesium you should dose each and every day.
  9. Monitor and fine-tune the daily dose as needed. If magnesium is slowly rising, reduce the daily dose by about 10%. If magnesium is slowly falling, increase the daily dose by about 10%.

Example for a 100-Gallon Aquarium

Day 1 at 8pm: 1300 ppm desired level

Day 5 at 8pm: 1270 ppm current level

5-day magnesium requirement: 241.9 mL

Daily magnesium requirement: 48.4 mL per day