Not all salt mix is created equal when it comes to your aquarium. That presents the question, what are the differences between the various salt mix options, and does it really matter when choosing one for my aquarium?

What is Salt Mix?

Salt mix, or more accurately said "seawater mix", is a dry granular formula that contains a variety of compounds and elements at the exact ratio they are found in natural seawater. It is far different from your everyday table salt, rock salt, or Epsom Salt.  It is intended to be mixed with pure H2O to create natural seawater. While seawater does contain a significant amount of sodium chloride salt, there are a variety of other important elements too. 

Composition of Seawater:

  • 96.5% H2O - good ol' fashioned water
  • 2.5% Salt - mostly sodium chloride salt but there are other types of salt found in seawater too
  • 1% Other - minor and trace elements 

Choosing The Right Salt Mix

When choosing a salt mix for your tank, it is best to choose based on the target parameters of your particular aquarium from a name brand you trust.  The reality is, any of the seawater mix brands we carry will work great for your saltwater aquarium. The most important thing is to pick a mix and stick with it. Changing up your salt mix brand is when you run into trouble because it will change the chemical composition of the water.  

What is the difference?

The most obvious difference between the various brands of seawater mix is the price. You can pay as little as $0.30 per gallon and as much as $0.55 per gallon or more; the price difference is significant when you're purchasing a 200-gallon mix once a month. With that in mind, a majority of the salt mix brands are going to be priced right at about $0.50 per gallon with just a couple of outliers in the really affordable or really expensive range. Being that salt mix is an ongoing expense, the cost is important but then again, most of the popular mixes cost about the same anyway. 

Each salt mix has a particular ratio of elements to achieve a set of target parameters, specifically the level of calcium and alkalinity or "major elements". Just like the price, however, most salt mixes are very close to one another and provide parameters within the typical range a saltwater aquarist would target with just a couple of outliers. Exactly why you can pretty much find success with any of the available salt mix options but if you're particular about the parameters in your reef tank, the salt mix choice can make a difference. 

Typical Major Element Parameters of Seawater Mix:

  • Calcium: 400-425ppm
  • Alkalinity: 7 - 9 dKH

Salt Mix with Elevated Calcium Levels:

Salt Mix with Low Calcium Levels

Salt Mix with Elevated Alkalinity Levels

Salt Mix with Low Alkalinity Levels

While cost and parameters are the most important, there are some other things to consider. Some salt mixes will dissolve quicker than others, some have specific mixing requirements, and some brands are known to contain impurities that will leave a residue behind in your mixing bucket. The good news is you can mitigate those effects with proper mixing techniques.

Our Top Picks

Most Budget-Friendly: Instant Ocean Sea Salt

Best for Beginners Who Want a Reef Tank: Instant Ocean Reef Crystals or Red Sea Coral Pro

Best for FOWLR (Fish Only) Tanks: Tropic Marin Classic or Brightwell Aquatics NeoMarine

Best Practices For Mixing Saltwater

  1. Read and follow the manufacturer's instructions
  2. Start with room temperature RO/DI water measuring 0 TDS and +/- 70°F
  3. Use a utility pump to stir the water and dissolve the salt mix
  4. Slowly add dry salt mix until salinity is reached (35 ppt or 1.025 SG)
  5. Add a heater and bring the water up to 78°F
  6. Allow it to mix for at least 24 - 48 hours before use (with the exception of Red Sea Coral Pro which mixes for a maximum of 4 hours)
  7. Water can be stored for up to 4 weeks with a tight-fitting lid

Learn More With BRStv: Top 15 Salt Mix Mistakes