
Magnesium
G2200 · 500ml
Essential for maintaining balance between calcium and alkalinity in reef aquariums. Magnesium is one of the most important yet often overlooked elements in reef keeping. It plays a crucial role...
Or build it into a bundle — save up to 6% ↓What it is, and who it is for.

Essential for maintaining balance between calcium and alkalinity in reef aquariums.
Magnesium is one of the most important yet often overlooked elements in reef keeping. It plays a crucial role in maintaining the delicate balance between calcium and alkalinity, helping prevent these elements from precipitating out of solution and becoming unavailable to your corals.
When magnesium levels are within the proper range, your aquarium will more easily maintain stable calcium and alkalinity levels—supporting healthy coral growth, improved skeletal development, and greater overall system stability. Without adequate magnesium, achieving this balance becomes difficult, often leading to inconsistent water chemistry and slower coral growth.
Key Benefits:
• Stabilizes calcium and alkalinity levels for easier reef maintenance
• Prevents precipitation of essential elements
• Promotes strong coral growth and coloration
• Supports the health of coralline algae and invertebrates
• Strengthens overall water chemistry balance in reef aquariums
Recommended Levels:
1200–1400 ppm
Directions for Use:
Add 5 ml of Magnesium per 100 L (25 gal) of aquarium water to raise magnesium levels by 3.75 mg/L (ppm).
Test magnesium levels regularly and adjust dosage as needed to maintain stability.
Build around the Magnesium.
It's already in your system below. Add the flow, filtration and dosing around it and the discount starts working — tiers climb as the build grows, and the reef meter fills with it.
Pick the right one, not the biggest one
The honest line-up from dosing & testing. Most buyers reading this page should buy the middle column.
Asked before checkout
The questions our support inbox actually gets.
Does it ship quickly?+
Orders placed before 2 PM ET on a business day leave the same day. Tracking is emailed the moment the label prints.
What if it's the wrong fit for my tank?+
Return it. 30 days, no restocking fee, refund to the original payment method. Better: tell us your tank first and we'll spec the system for free — half of all returns are sizing problems.
Who handles the warranty?+
We do. Everything carries the manufacturer's warranty and we run the claim for you — one email to us instead of a ticket queue.
How does the bundle discount work?+
Add items in the bundle builder: 2+ items saves 5%, 3+ saves 8%, 4+ saves 12%, and 5+ saves 15% off the whole system, applied at checkout.

Calcium
Magnesium
Jebao Doser 3.1 Single Dosing Pump