Magnesium Info

By PJS Tropical Fish Inc
October 11, 2026

PJS Reef Moonshiners Magnesium Info

PJS Supplement Mag Mix

PJS Supplement Mag Mix

Mastering Magnesium in the Reef Aquarium: The Complete Guide for PJS Tropical Fish & Reef Moonshiners

Maintaining a thriving saltwater aquarium takes more than just keeping the water clear; it requires a deep understanding of water chemistry. When it comes to building vibrant, skeletal coral structures, Magnesium (Mg) is the ultimate unsung hero.
As a premier resource for aquatic excellence, PJS Tropical Fish provides the specific elements, custom-blended foods, and expert-level tools needed to achieve flawless reef chemistry. If you utilize the revolutionary PJS Reef Moonshiners Program, mastering your magnesium levels is your very first step toward total tank success.

Purpose, Procedure, & Importance of Magnesium

Purpose

Magnesium’s primary purpose in a reef aquarium is to maintain high supersaturation levels of Calcium (Ca) and Carbonate (CO3). Without magnesium, these two components bind together and precipitate out of solution as calcium carbonate (limestone dust), rendering them completely useless to your corals.

Procedure

    1. Test Regularly: Test your water chemistry weekly using a reliable high-precision test kit or professional ICP testing.
    2. Calculate Your Dose: Utilize the PJS Reef Moonshiners DIY Calculator to compute the precise elemental weight required to safely shift your volume.
    3. Select Your Formula: Use PJS Mag Mix for large corrections and PJS Mag Maint to safely sustain daily stability.
    4. Dose Slowly: Always add high-concentration magnesium formulas into high-flow areas of your sump to prevent localized shock to corals and invertebrates.

Importance: What Processes and Functions Does It Support?

    • Skeletal Calcification Support: Corals like Acropora, Montipora, and LPS varieties need magnesium to actively deposit calcium carbonate into their skeletal matrix.
    • Coralline Algae Proliferation: That beautiful pink and purple crustose coralline algae requires substantial amounts of magnesium to grow and outcompete nuisance hair algae.
    • Enzymatic Function: In reef fish, invertebrates, and coral tissue, magnesium serves as an essential cellular co-factor supporting hundreds of enzymatic processes, cellular energy transfer (ATP), and neuromuscular health.

History & Unique Facts of Magnesium in the Hobby

History in the Hobby

In the early days of the saltwater hobby during the 1970s and 1980s, reef keeping focused almost entirely on specific gravity, pH, and rudimentary filtration. When hard coral (SPS/LPS) keeping exploded in the 1990s, hobbyists often faced “mysterious” drops in calcium, even when dosing heavily.
It wasn’t until the late 1990s and early 2000s that marine scientists and pioneer hobbyists highlighted magnesium as the missing link. Once magnesium supplements were introduced to the commercial industry, maintaining successful reef aquariums became a repeatable science.

Unusual and Unique Facts

    • The Irony of Coral Skeletons: While magnesium prevents calcium from solidifying in your water, hard coral skeletons actually incorporate about 1% to 3% magnesium directly into their mass.
    • The Green Connection: Magnesium is the central atom in chlorophyll molecules. This means the symbiotic zooxanthellae algae living inside your coral tissues rely heavily on magnesium to efficiently photosynthesize light into energy!
    • Sea Chemical Bulwark: Magnesium is the third most abundant ion dissolved in natural seawater, significantly outnumbering calcium.

How It Is Supplied & Ionic Balances

How It Is Supplied Now

In modern reef keeping, magnesium is supplied through high-purity raw chemicals, tailored liquid supplements, and advanced hybrid media. Most notably, the PJS Reef Moonshiners DIY Program lets hobbyists customize their dosing regimen by using precision formulas to match exact consumption.

Ionic Balances

Magnesium behaves in tandem with other critical chemical compounds. It acts as a safety buffer that keeps your basic foundation elements in a perfect liquid dance.
    • Works in Conjunction With: Calcium and Alkalinity (Carbonates). Magnesium acts as a chemical blocker. It sits on nascent calcium carbonate crystals, preventing further crystal growth and keeping both elements freely floating for biological absorption.
    • Needed by Other Elements: Strontium, Barium, and Boron depend heavily on stable magnesium levels to integrate correctly into biological reef skeletons without causing brittle structural faults.
    • Keeping Chloride and Sulfur in Ionic Balance. Monitor the ionic balance of these to determine the use of Mag-Mix or Mag-Maint if your Sulfur is decreasing, due to the byproduct/carrier salts chloride and sodium in Calcium, Magnesium and other chemical additives.

Proper Magnesium Levels

To maximize coral growth and maintain optimal aquatic health, your aquarium water parameters must parallel natural marine baselines.

Environment Optimal Magnesium Range
Natural Marine Environment 1,280 – 1,320 ppm
Captive Reef Aquarium Environment 1,350 – 1,450 ppm

Note: In closed aquarium systems, keeping magnesium slightly elevated (around 1,400 ppm) provides a wider safety buffer for rapid coral skeletal growth and enhanced stability.

Selecting the Right Dose: PJS Mag Mix vs. PJS Mag Maint

Choosing the correct product variant from the PJS line is paramount for chemical safety and preventing unnecessary system shock.
       [Your Current Magnesium Levels]
                     │
          Does it need a large adjustment?
           /                         \
       (YES)                         (NO)
         │                             │
 [Use PJS Mag Mix]             [Use PJS Mag Maint]
 • Heavy concentration         • Perfectly balanced formula
 • For corrective targets      • For stable daily maintenance

PJS Mag Mix

    • When to Use: Use this when your initial testing shows a major depletion in magnesium levels (e.g., your tank reads 1,200 ppm and you need to bring it up to 1,380 ppm).
    • Characteristics: A heavily concentrated raw elemental formula engineered to make substantial, controlled upward shifts in your water chemistry without swinging your salinity completely out of balance.

PJS Mag Maint

    • When to Use: Use this as your standard daily or weekly maintenance dose once your target levels have been achieved.
    • Characteristics: A perfectly balanced magnesium solution formulated to keep pace with everyday consumption. It ensures your system experiences absolute stability without localized ionic spikes.
    • Where is your Sulfur? If ionic balance to chloride is low, time for Mag-Maint.

Benefits vs. Risks

Benefits

    • Accelerated Coral Growth: Maximizes the uptake of calcium and alkalinity, facilitating rapid tissue and skeletal expansion.
    • Algae Suppression: Helps support healthy coralline algae growth, which naturally blankets live rocks and prevents nuisance turf or hair algae from taking hold.
    • Vibrant Tissue Health: Works beautifully alongside nutrient-rich target foods like PJS RFL Filter Feeder Food and specialized PJS Amino Acids Blends to boost tissue regeneration and color.

Risks

    • Dosing Blunders (Overdosing): Pushing magnesium beyond 1,600 ppm can cause lethargy in reef fish, tissue sloughing in delicate corals, and can cause snails and hermit crabs to become narcotic, losing their grip on rockwork.
    • Underdosing Precipitation: Letting magnesium slip below 1,250 ppm will trigger rapid precipitation. Your calcium and alkalinity levels will crash, leading to pump impeller failure and coral starvation.

Frequently Asked Questions (FAQ)

Can I use medication or food to fix a magnesium deficiency?
No. While premium foods like PJS Brand Frozen Flat Packs provide excellent nutritional trace minerals, they cannot fix a structural elemental deficit. A true macro-element deficiency must be safely corrected via direct water chemistry adjustment using PJS Mag Mix.
Will low magnesium cause my corals to lose color?
Indirectly, yes. When low magnesium disrupts calcium and alkalinity stability, corals become stressed, stunt their growth, and may bleach or brown out. To aid stressed corals during water adjustments, supplement with a healing recovery blend like PJS Amino Acids MD (Medicinal).
How much can I safely raise my magnesium per day?
It is recommended to raise your magnesium by no more than 30–50 ppm per day using your PJS Reef Moonshiners DIY Calculator instructions to prevent sudden osmotic stress in fish and delicate inverts.

PJS Tropical Fish Inc

I have been in the hobby for over 45 years. I have been in the Industry for 40 years at many levels from a breeder, to traditional retail store owner, to regional wholesaler.