Aquaforest AF Magnesium Test Kit | Reef Mg Test for Saltwater Aquariums – NT Labs

Keep your reef tank dialed in with theAquaforest AF Magnesium Test Kit— a fast, accurate liquid titration test for measuring magnesium (Mg) in saltwater aquariums. Magnesium is one of the three core reef-foundation parameters (calcium, alkalinity, and magnesium); maintaining it in the 1250–1350 ppm range is critical for healthy coral growth and skeletal development. Browse more water testing kits at Squeaky’s Aquatics.

Why You Need to Test Magnesium

• Stabilizes calcium and alkalinity:Magnesium prevents calcium and alkalinity from precipitating out of solution, which is why dosing one without testing the others rarely produces stable results.
• Coral skeletal health:Stony corals (LPS and SPS) incorporate magnesium directly into their skeletons. Low Mg = poor growth.
• Coralline algae growth:Healthy magnesium levels support coralline algae spread across rock and glass.
• Reef stability:Test weekly or bi-weekly in established reef tanks; more often in heavily-stocked SPS systems.

How It Works

The kit uses a two-stage liquid titration method. Add reagents to a small saltwater sample, then count drops of titrant until the color change occurs — each drop represents a known increment of magnesium. Results are read directly in mg/L (ppm).

• Test range:Suitable for typical reef-tank Mg levels (~1000–1500 ppm)
• Test count:Approximately 50 tests per kit
• Use frequency:Weekly recommended for reef tanks; more often when actively dosing two-part or balling-method supplements
• Compatibility:Saltwater / reef aquariums only

Specifications

Recommended Pairings

• Red Sea Reef Foundation C — Magnesium (Mg) 500 mL — dose to raise Mg back into range
• Red Sea Reef Foundation Pro Multi Test Kit (Ca, Alk, Mg) — alternative all-in-one foundation kit
• Salifert Calcium Test Kit — pair with magnesium testing for full reef-foundation coverage
• Salifert KH/Alkalinity Test Kit — the third leg of the reef-foundation tripod
• Browse all Aquaforest products

Frequently Asked Questions

How often should I test magnesium?
Weekly is a good baseline for established reef tanks. If you’re actively dosing a two-part or balling-method supplement system, test more often — every 3–4 days — until your consumption rate is stable.

What’s the ideal magnesium level for a reef tank?
1250–1350 ppm is the typical target. Some SPS-heavy systems run at the higher end of that range.

Can I use this on a freshwater tank?
No. This kit is calibrated for saltwater Mg levels. Freshwater systems have a different magnesium chemistry and don’t typically need Mg testing.

How long do the reagents last?
Unopened reagents last 2–3 years from manufacture date. Once opened, use within 12 months for best accuracy and store away from heat and direct light.