How to Choose Aquarium Salt

How to Choose an Aquarium Salt

A high-quality aquarium salt mix is essential for creating the ideal saltwater for a reef aquarium. While those new to the reef hobby may think mixing saltwater is as simple as adding sea salt to tap water, experienced hobbyists know the process is much more complex. Recent scientific advancements have improved the formulation and purity of reef salt and allowed the replication of natural ocean environments better than ever before. Choosing a good quality salt mix can significantly enhance coral health and coloration.

What is Aquarium Salt?

At the most basic level, aquarium salt is a mixture of calcium, alkalinity, magnesium, and various trace elements. When mixed with RO-DI water, a good quality reef salt will mimic actual ocean water. Real ocean water varies from one location to another across the globe, and similarly, the parameters of different salt mixes differ from one brand to another.

The Difference Between Aquarium Salt & Sea Salt

Aquarium salts vary significantly from the standard sea salt in the grocery store. While most aquarium salt mixes contain around 70 unique trace elements, store-bought salt is refined and contains considerably fewer trace elements.

Fritz RPM Salts Courtesy of Fritz Aquatics
Fritz RPM Salts Courtesy of Fritz Aquatics

What Corals Need From Aquarium Salt

The three primary components of reef salt are calcium, alkalinity, and magnesium. These are the same three components that are critical for coral growth and health. When mixed to a salinity of 35 ppt, calcium, alkalinity, and magnesium should fall in the following ranges:

Calcium: 420-450 ppm

Alkalinity: 8-12 DKH

Magnesium: 1250-1350 ppm

Aquarium reef salt also contains trace elements in their proper concentrations. Some of the most important trace elements include Iodine, Iron, Zinc, Molybdenum, Copper, and Nickel.

What Makes a Good Quality Salt?

A good quality salt should have the following components:

  1. Proper Levels of Calcium, Alkalinity, and Magnesium: This is a minimum baseline requirement for any salt. Today, nearly all aquarium salts provide adequate calcium, magnesium, and alkalinity.
  2. Proper Levels of Key Trace Elements: High-quality reef salts set themselves apart because they contain trace elements at the proper levels. The scientific analysis printed on the bag or bucket of salt will break down what is in a particular salt.
  3. Dissolvability: How well the salt mixes into RO-DI water is a good indicator of salt quality. Some salts will fully dissolve within just a few hours. However, it is not uncommon for it to take up to 24 hours to dissolve fully. If it takes significantly longer than 24 hours, the salt quality is likely poor.
  4. Low Impurities: A good quality salt should be crystal clear after 24 hours of mixing. If your salt mix leaves behind many impurities at the bottom of the mixing container, it is time to look for a different salt. Also, look for a salt made with pharmaceutical-grade chemicals.
  5. Consistent Mix: One challenge for salt manufacturers is maintaining consistency throughout each batch and each bag or bucket. Some reefers try to maximize the consistency of their saltwater by mixing the whole container at a time or rolling the bucket or container thoroughly before adding the mix to the water.
Periodic Table
Periodic Table

Comparison Chart of Popular Salt Mixes

Here is a breakdown of the critical components of some of the most popular salt mixes on the market today. The average cost per gallon of each salt mix is based on the most cost-effective package size for each type of salt.

Type of Salt
Instant Ocean Reef CrystalRed Sea Reef SaltRed Sea Coral Pro SaltTropic Marin Pro Reef SaltBrightwell NeoMarine SaltFritz RPM Salt
Recommended Salinity35 ppt35 ppt35 ppt35 ppt35 ppt35 ppt
Calcium490ppm420-440 ppm430-450 ppm440 ppm420 ppm400-450 ppm
Alkalinity13 dKH7.8-8.2 dKH11.8-12.2 dKH8 dKH11 dKH8.0-9.0 dKH
Magnesium1440 ppm1250-1310 ppm1280-1340 ppm1350 ppm1380 ppm1300-1400 ppm
Ideal Tank TypeMixed ReefLow-Nutrient Mixed ReefMixed Reef & SPS FragsSPS DominantMixed ReefMixed Reef
Cost Per Gallon$0.50$0.49$0.49$0.55$0.49$0.43
Aquarium Salt Comparison Chart

How to Choose the Best Salt for Your Tank

By now, you should understand that there is no one size fits all solution when it comes to determining the best aquarium salt mix on the market. Each aquarium has different goals, and each salt has particular benefits that may or may not match those goals. When picking a salt, the most important thing is to pick a salt mix and stick with it. Constantly changing salt mixes is not recommended as it can cause fluctuations in major and minor elements in the tank. And don’t sweat it if your chosen salt mix doesn’t perfectly replicate your ideal parameters. Most won’t. The goal is to get close and supplement your tank with additives to make up for any deficiencies.

While there is no one-size-fits-all when selecting the perfect salt mix for your reef tank, we have recommended some salts we like based on the type of tank.

Type of TankSalt RecommendationFactors
Beginner Soft Coral ReefInstant Ocean Reef CrystalsBudget-friendly, provides a proper base salt mix that can be customized, mixes quickly
Intermediate Mixed ReefRed Sea Reef SaltElevated calcium and magnesium levels, complete salt mix that contains 57 unique elements
Advanced SPS Dominant ReefTropic Marin Pro Reef SaltElevated calcium and magnesium levels, pharmaceutical grade, balance of all 70 trace elements
Aquarium Salt Recommendation Chart

How to Prepare Salt for Use (A Step by Step Process)

Aquarium Salt Mixing Illustration
Aquarium Salt Mixing Illustration
  1. Select salt.
  2. Determine how much water to make.*
  3. Add the required amount of RO/DI water to a large mixing container. Don’t fill it to the top.
  4. Following the dosage recommendations on the salt’s packaging, weigh or measure out the proper amount of salt.
  5. Turn on a mixing pump and slowly add the salt into a high flow area of the mixing container.
  6. Mix water per the manufacturer’s recommendation. Some salts will be ready within a few hours; however, most salts require 12-24 hours to fully dissolve.
  7. Test salinity. The optimal range is 1.024 – 1.026 (32 – 35 ppt).
  8. Add additional salt to raise the salinity or RO/DI water to lower the salinity.
  9. Mix water for a minimum of 1 hour and ideally overnight.
  10. Retest salinity. If needed, add additional salt to raise the salinity or RO/DI water to lower the salinity and mix again.
  11. Heat the mixed saltwater to the same temperature as the tank water.

* We recommend making the same amount of water every time. The exact amount of water = the same formula every time.

We hope this guide has helped you see the value of selecting the proper salt mix for your reef tank. Salt mix is yet another element in a reefers toolkit that allows you to improve the environment you can create for your corals and other livestock. While the type of salt is crucial to your success, even more, important is to ensure that you are mixing the water to the proper salinity level.

Please contact our support team if you have any additional questions about salt mix or mixing your saltwater.

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