How to Choose Aquarium Additives: Trace Elements

How to Choose Aquarium Additives Part Two: Individual Elements

Welcome to part two of our How to Choose Aquarium Additives article. In part one, we discussed selecting a primary dosing system, like traditional 2-part and newer, more advanced dosing systems, like ATI Essentials Pro. While these primary dosing systems cover most of an aquarium’s dosing needs, additional dosing of individual elements may be required. In part two, we will review the available major and trace elements and provide guidance on which elements may be worth adding to your system.

Major vs. Trace Elements

Major elements are found in high concentrations in saltwater, while trace elements are found in low concentrations.

Major Elements

The major elements of reefkeeping include calcium, magnesium, and alkalinity. Proper levels of these elements are essential for maintaining a successful saltwater aquarium.

ATI Iodine Trace Element
ATI Iodine Trace Element

Trace Elements

Trace elements make up less than one percent of saltwater; however, many are essential for biological processes that impact coral health, growth, and coloration. Trace elements include phosphate, nitrate, iodine, zinc, potassium, strontium, manganese, molybdenum, and many others.

How Do I Know I Need to Dose Individual Elements?

Testing is the best way to know if you need to dose trace elements individually. Reefers should carefully watch their coral’s growth and coloration, and if they notice a downturn in coral health, they should test their tank’s parameters. First, check major components, like calcium, alkalinity, and magnesium, and then check trace elements. For trace element testing, an ICP test, like ATI ICP Labs ICP-OES Water Analysis, provides accurate readings for a large number of trace elements.

ATI ICP-OESS Water Analysis Machine
ATI ICP-OES Water Analysis Machine

Do I Need to Dose Individual Elements

The simple answer is yes. Although trace elements account for a small portion of the makeup of saltwater, they are crucial to numerous biological processes that allow corals to grow, heal, and color up. While many dosing systems provide some trace element coverage, they may not offer full coverage. Also, systems deplete these elements at different rates, so keeping everything at the proper levels is challenging without individual dosing.

Individual Elements Tiers Chart

Reef Elements Tiers Chart
Reef Elements Tiers Chart

Tier One: Calcium, Alkalinity, Magnesium, Nitrate, & Phosphate

Tier one elements are the most crucial to the success of your reef tank and are essential to various biological processes. Most primary dosing systems contain calcium, alkalinity, and magnesium. Nitrate and phosphate are generally available in the water, however, usually not in the correct proportions.

Tier Two: Iodine, Nickel, Iron, Zinc, Cobalt, Potassium, Strontium, Manganese, & Molybdenum

Elements in tier two are the most essential trace elements to cover to maximize coral health, color, and growth.

Tier Three: Barium, Boron, Bromine, Chromium, Fluorine, Lithium, & Vanadium

Elements in tier three are important to the primary biological functions of corals. They can often be maintained with consistent water changes or dosed manually as needed.

Tier Four: The rest of the measured elements within a reef aquarium fall into the category of tier four. This tier is of lesser importance to the biological process of coral growth, but should still be monitored to ensure they do not fall into a range that could endanger the health of your system.


Trace element coverage does come at a price and will vary significantly based on the tank size, the number of corals, and the type of corals. Consistent testing, especially in the beginning, will determine what trace elements you need to dose frequently. To maximize your budget, you can purchase a trace element additive designed to cover many elements in fewer bottles. However, this option does not work well if your system depletes some trace elements faster than others. The primary alternative for dosing trace elements is frequent and significant water changes, however, this is only really a viable option for nano and other small volume tanks.

We hope this guide has helped summarize which trace elements you should consider adding to your dosing routine. While they only account for a small percentage of your water chemistry, trace elements play a vital role in coral health, growth, and color. If you have any additional questions about trace elements or are seeking recommendations, please contact our support team.

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