Maintaining proper water parameters like calcium, alkalinity, and magnesium is crucial for a thriving reef tank. But what should you do when magnesium levels start creeping too high? Don’t panic – with a few simple techniques, you can get those levels down to where they need to be.
If you’re short on time, here’s a quick answer to your question: target water changes, use a phosphate remover, and dose magnesium consuming corals to lower high magnesium levels in your reef tank.
In this comprehensive guide, we’ll cover everything you need to know to lower high magnesium levels in your reef tank. You’ll learn what causes high magnesium, how to test for it, what levels to aim for, and step-by-step methods to lower magnesium using water changes, chemical media, and strategic coral placement.
What Causes High Magnesium?
Seawater Makeup
Natural seawater contains approximately 1,300 ppm of magnesium. When we make artificial seawater or top off evaporation with freshwater, the makeup water can slowly increase magnesium over time. Performing routine partial water changes is the best way to combat creeping magnesium levels from seawater makeup.
Aim to change 10-20% of the display tank volume monthly. This will maintain all parameters at appropriate concentrations.
Supplements
Many reef supplements contain magnesium as an essential ingredient. For example, magnesium is a vital component of most buffer or alkalinity supplements used to maintain pH. While these additives provide benefits, they also contribute to rising magnesium when used excessively.
It’s best to follow dosing instructions carefully and test levels frequently. Consider switching products if magnesium climbs above the target range.
Alkalinity Additives
The most common culprit for magnified magnesium is alkalinity maintenance. Supplements like baking soda or natural seawater contain high levels of magnesium. When alkalinity needs to be raised, these additions can rapidly increase magnesium content.
For example, baking soda is approximately 50% magnesium by weight. Even small, frequent doses add up over time. Instead, switch to a balanced carbonate supplement that contains minimal magnesium. This allows alkalinity to be maintained without spiking magnesium levels.
Measuring and Testing Magnesium
Test Kits
To measure magnesium levels, hobbyists typically use test kits that utilize colorimetric analysis. Popular options include Salifert and Hanna checkers, which provide reasonably accurate readings. These kits involve adding reagents to a water sample and comparing the resulting color to a color chart to determine the magnesium concentration (typically measured in parts per million or ppm).
Test kits are affordable, easy to use, and give rapid results.
Other Parameters to Test
While measuring magnesium is important, it doesn’t give you the full picture. Calcium, alkalinity, and magnesium have a complex interdependent relationship, so they should be monitored together. For example, if calcium falls, magnesium may increase to unhealthy levels.
Some hobbyists also suggest tracking sodium, potassium, and strontium. By regularly testing multiple parameters, you can better understand fluctuations and maintain ideal mineral levels.
Ideal Magnesium Range
The optimal magnesium level for a reef tank is generally considered to be between 1200-1400 ppm. However, the ideal range can vary slightly based on other factors:
- For tanks with low alkalinity, aim for 1300-1500 ppm magnesium.
- Tanks with faster growing SPS corals often thrive with magnesium around 1350-1450 ppm.
- If calcium is maintained at 440-460 ppm, magnesium levels at the lower end of 1200-1400 ppm are usually sufficient.
Regardless of the target number, stability is crucial – sudden significant magnesium fluctuations can stress inhabitants. By frequently testing and making gradual adjustments, your tank’s creatures can thrive.
How to Lower Magnesium
Targeted Water Changes
One of the most effective ways to lower magnesium (Mg) levels is through targeted water changes using reverse osmosis (RO) or distilled water with little to no Mg (BRS TV). This allows you to gradually dilute Mg while monitoring calcium, alkalinity, and other parameters.
Aim for 10-20% water changes 1-2 times per week until your target level is reached. Larger or more frequent water changes run the risk of crashing your tank’s chemistry.
Use a Phosphate Remover
Media designed to remove phosphate, such as Rowaphos, can also reduce magnesium as a secondary effect. As water flows through the media, Mg ions are adsorbed and removed along with the primary target of phosphate. This passive method avoids large chemistry swings compared to water changes.
Monitor params closely and replace media regularly for effectiveness. ☀️
Strategic Coral Placement
Certain corals like acropora and montipora use higher amounts of magnesium for rapid skeletal growth. Placing large colonies in areas with higher flow can accelerate Mg removal through uptake. This ecosystem-based approach allows inhabitants to gradually consume excess nutrients.
🦠🐚 Just be careful not to exhaust reserves too quickly! Rotate coral placement every few months for best results.
Implementing a multi-pronged strategy is key to safely lowering magnesium levels without shocking your system. Patience and gradual changes give your tank ecosystem time to rebalance at new parameters. Consistent testing helps dial things in just right for thriving, healthy corals! 🌟🎉
Maintaining Proper Levels
Control Inputs
Controlling the inputs into your reef tank is crucial for maintaining appropriate magnesium levels. Here are some tips:
- Use reverse osmosis/deionized (RO/DI) water when mixing new saltwater. RO/DI removes magnesium, allowing you to have greater control over magnesium concentrations.
- Limit feeding to avoid phosphates and excess nutrients that can deplete magnesium. Overfeeding can lead to aggressive algae growth.
- Carefully select salt mixes and two-part solutions, targeting 8-1350 ppm calcium and 1200-1350 ppm magnesium.
- Use magnesium supplements (like Kent Tech M Essential Elements) as needed per test results.
- Do larger, less frequent water changes (e.g. 20% biweekly) rather than smaller, more frequent ones to allow magnesium to stabilize.
Test Regularly
It’s important to test your reef tank’s magnesium levels frequently to catch any fluctuations and make adjustments. Here are some tips:
- Test 1-2 times per week to start until levels stabilize.
- Use a quality calcium test kit that also measures magnesium.
- Test prior to water changes, several hours after dosing supplements.
- Keep a log to track trends over time.
- Ideal magnesium levels are around 1300-1350 ppm. If levels drop below 1200 ppm, supplement as needed.
- A sudden crash or spike in magnesium warrants further investigation (e.g. equipment malfunction).
Balance with Calcium
Magnesium and calcium work synergistically in reef tanks, so maintaining proper balance is key. Here are some tips:
- Aim for a calcium:magnesium ratio of 8:1 to 12:1 for optimal coral growth.
- When dosing two-part supplements, use them in proper proportions to achieve this ratio.
- If raising calcium, increase magnesium levels accordingly to maintain balance.
- Monitor alkalinity along with calcium and magnesium. Keep alkalinity 8-12 dKH.
- Routine water changes help restore normal balances if levels shift.
By controlling inputs, testing regularly, and balancing calcium and magnesium, reef tank hobbyists can maintain optimal magnesium levels. Stable magnesium promotes vibrant coral growth and health. Be diligent with routine testing and logging results to catch any fluctuations early.
Conclusion
Keeping an eye on magnesium while also maintaining ideal levels of calcium and alkalinity can seem daunting. But with consistent testing, strategic water changes, phosphate control, and proper coral placement, you can bring your reef tank’s magnesium down to proper levels.
Your corals will thank you with vibrant growth and rich colors when all parameters are balanced and stable.
Modifying water chemistry does take some time and patience. But the reward is a thriving reef bursting with life. We hope this guide gave you a strong foundation for lowering magnesium and optimizing overall water quality for a healthy marine aquarium.
