What is the best reef aquarium salt mix? A product review of popular reef salt brand options

Ask the question: “What is the best reef aquarium salt mix for a reef tank?” on any saltwater aquarium forum, and you are likely to get a whole host of answers.

Forums are littered with complaints and praises about nearly every brand of marine aquarium salt mix. Generally speaking, each person on these forums speaks to how much success they’ve had with this marine salt vs. that reef salt mix.

I’m generally grateful they shared their experience, but unclear about how or why they perceived their experience to be so different.

How is a saltwater aquarium owner supposed to sort through the options to make the best choice for their own tank? Put another way, how can you and decide which is the best marine aquarium salt mix for your own circumstances and budget?

Short on time? Jump to the conclusion

This is a fairly long article. If you want to cut to the chase and check out the marine salt mix I personally use in my home aquarium and recommend

Click here

To do your own comparison and check out a few different brands,

Click here instead

A product review of the best reef aquarium salt brands: comparing the labels

In addition to the fact that every aquarium owner has their own opinions and observations about how a particular marine salt mix worked for them in their tank, another challenge with comparing brands of aquarium salt is that the package sizes and the composition of the salt can vary widely from one brand to the next.

Some parameters can be compared, others need to be adjusted for the size of the container.

A comparison across 3 important reef aquarium water parameters

Marine salt mixes aren’t just sodium chloride, like your table salt, they have mineral content which is important to help keep a happy reef. For comparison sake, there are three important components of an aquarium salt mix:

  1. calcium
  2. alkalinity
  3. magnesium.

The best salt mix would be one with high levels of each of these parameters, at a reasonable price. Below is a table of the reported values from the labels of popular aquarium salt brands.


Calcium is an important component in aquarium salt. It is used by the corals and other invertebrates in the tank to build their stony skeletons. A typically recommended concentration of calcium in a reef aquarium is 400 ppm. PPM stands for part per million, which in this case means 400 out of every million parts of mixed saltwater will be calcium.


Alkalinity is related to the pH, or relative acidity of the water. Almost by definition, pure water is not acidic or basic, but water with aquarium salts mixed in is considered to be relatively more basic or alkaline (it has more alkalinity). Alkalinity is important because it allows us to estimate how much bicarbonate is in the water–and bicarbonate is another one of those things that are important to coral growth.

The ideal range for alkalinity in a saltwater aquarium is 8-11 dkh.


Magnesium is one of the most abundant of the ‘trace’ minerals in saltwater. It ‘works’ with calcium and impacts the balance of alkalinity in the aquarium water. The recommended range for magnesium in a healthy saltwater aquarium is ~1250 to 1400 ppm.

How do the major aquarium salt brands stack up across these important parameters?

Several of the top aquarium salt brands are listed below, along with the values for calcium, alkalinity, and magnesium, as reported on their product labels. This list includes:

Look across these marine reef aquarium salt mixes to compare the levels of calcium, alkalinity, and magnesium

The reported values of calcium, alkalinity, and magnesium are listed in the table, for each salt brand and the recommended range/value is included in the bottom.  These are approximate values, not absolute. The first thing I noted was that all of the best marine salt mixes compared here post appropriate levels of each of the three water parameters: calcium, alkalinity, and magnesium

A few of the marine salt mixes have standard ranges below the recommended levels. These are noted (in red).  I don’t expect the fact that a few drifted slightly below my previously noted ideal range to be meaningful. I doubt there are any data, anywhere, to suggest those levels are demonstrably less effective than the rest of the mixes.

So while you may be inclined to make a decision based on that (and you might as well, you don’t have a lot of other information to go on), I also encourage you to not to over-react in the event the salt you are currently using (or intended to use) is on the low end of the list here for any of these values.

A few reef salt mix conclusions

  1. I would feel comfortable purchasing and use any of the above reef salt brand options for a tank with mushrooms, zoanthids, soft corals, LPS corals or SPS corals
  2. If I observed an issue in my tank that I suspected of being related to a value…like alkalinity…for example. I might test out a higher alk salt to see if it helps and go either up or down on the scale to see if that makes a difference.
  3. If I was dosing one or more of those nutrients into my reef tank, and I knew how quickly my tank depleted those nutrients, I would use it as one additional factor into calculating the cost (or cost savings) of one salt versus another.

Comparing the costs of the best aquarium salt mixes

Since all of the major salt brands listed above have the most important water parameters covered, one could make an argument that there is no single best aquarium salt mix and that they are all pretty much the same (I suspect the marketing brand managers would cringe if they read that). One thing you can objectively compare is the cost (I probably made the marketing managers cringe for a second time there).

At first glance, however, it can be slightly challenging to compare the cost across salt brands, because the standard ‘bucket’ of salt can make 150, 160, 170 or even 200 gallons of saltwater, depending on the manufacturer.

That makes the match nearly impossible for the average person (average dimwit writing this article, at your service). What I recommend you do to create a fair comparison is to take the price per bucket or box of salt and divide it by the number of gallons per container to determine the cost per gallon.

Here are a few hypothetical prices for each of the brands listed above that are approximated based on what I’ve seen. Please note, prices can fluctuate a bit online, so it’s typically best to go to the websites directly to do your own math and get the most accurate number. Below here is an example calculation based on some reasonable pricing estimates.

Reef salt comparison chart

By creating the cost per gallon metric, it becomes a little easier to tell if the $77 bucket of Tropic Marin that makes 200 gallons is a relatively more or less expensive option than the $77 bucket of Red Sea Coral Pro salt that makes 175 gallons–or if the $40 boxes of Instant Ocean and Kent Marine Reef Salt are the same.

In the table above, I calculated the cost per pound of aquarium salt mix and the cost per gallon of mixed saltwater.

Cost of Supplementing Your Aquarium Water to Add to the Marine Salt Mix

In order to determine which brand is the best aquarium salt mix, you also have to consider the cost of supplementing your aquarium water. If you have a lot of stony corals (SPS or LPS) or clams, you may notice that the calcium levels in your tank steadily decline as the animals inside your tank deplete the natural calcium levels to build their stony skeletons and shells. In that instance, you probably want to supplement your aquarium water with a calcium reef supplement like kalkwasser (calcium hydroxide).

If you regularly dose calcium in your tank, you would benefit from doing one further quick cost analysis when picking the best aquarium salt mix for your reef tank.  So while my analysis above is just a straight cost per gallon, I encourage you to do your own math to figure out an ‘all-in’ cost per gallon once you account for supplements, if you add any.

If, for example, you buy Tropic Marin salt (at $0.39/gallon) and you routinely add calcium to your tank in the form of kalkwasser at an additional cost, it may be reasonable for you to consider switching to a brand like Seachem ($0.33/gallon), saving money and raising your calcium concentration by 165 parts per million–you may find you no longer need to add a calcium supplement between water changes, in that instance.

So what is the best reef salt mix?

For me, the best reef salt mix, of all the salts om the market, when you weigh all the various factors, is Instant Ocean.

Why is Instant Ocean Salt Mix the best?

Because the Instant Ocean Salt Mix is a great quality product at a reasonable price. That’s the brand I use. I tried to ‘upgrade’ to the Reef Crystals brand of salt (also made by the same company).

I can report that I didn’t personally see any benefit to that more expensive brand compared with Instant Ocean Brand.

Where to get more information about your specific reef aquarium salt mix

If you are interested in information beyond the scope of what is covered here in this saltwater mix review of the best reef salt mixes, you may want to explore a few of the individual manufacturer sites for more information:

What aquarium salt mix do I use and where do I get it from?

For the last several years, I’ve purchased my salt from Amazon.com (affiliate link).

No more lugging around buckets. The buckets come shipped directly to my door. No more drive time. No more hassle at all. And when the bucket arrives, I’m giddy, like a little kid on his birthday.

The product is Amazon Prime eligible (which means they will send it via 2-day shipping for free for Amazon Prime members) and also qualifies for their free Super Saver Shipping option too. What a great deal! You couldn’t beat that with an Acropora (get it? nickname..stick…).

If you decide to buy a bucket of salt or any other product on Amazon after clicking on one of the affiliate links above, I will earn a small commission. No pressure at all. You can find the same products, at the same prices by searching on your own, but thank you if you decide to use one of the links to make a purchase. Every little bit of support helps me continue to produce this website.

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What do you think?

How about you–what do you think is the best marine salt mix and why? Please leave a comment below to let us know what your experience is.