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

Ask the question: “What is the best marine aquarium salt mix?” on any reef 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, with each person holding firm beliefs about perceived benefits a given aquarium salt mix has had on their tank. There is no problem with opinions. It is great that people are sharing their experiences, but how is a saltwater aquarium owner supposed to sort through the options to make the best choice for their own tank and decide which is the best marine aquarium salt mix for their own circumstances and budget?

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

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

Click here instead

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

In addition to the fact that every aquarium owner has their own opinions and observations about how a particular aquarium 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

Three important components of an aquarium salt mix are calcium, alkalinity, and 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 is 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 aquarium salt mixes compared here post appropriate levels of each of the three water parameters: calcium, alkalinity, and magnesium.

A few of the 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 aquarium salt mix conclusions

  1. I would feel comfortable purchasing and using any of the above reef salt mix 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 in 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.

Seachem Reef Salt marine aquarium salt Image by Nat Tarbox Creative Commons License on Flickr

Comparing the costs of the best aquarium salt mixes

Since all of the major 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 like to do to create a fair comparison is to take the price per bucket and divide it by the number of gallons per bucket to determine the cost per gallon. Here are the prices for each of the brands listed above that I pulled down from Amazon.com a few nights ago. Please note, I’ve been watching the prices here for a few weeks now and noticed that the price is currently fluctuating A LOT, so this might not be the price when you look–but I think you’ll see how I do the math and get the point.

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 Aquarium 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.

Where to buy the best marine aquarium salt mix for a reef tank

It is also difficult sometimes to get saltwater aquarium hobbyists to agree on the best place to buy aquarium salt mix. Some champion the virtues of supporting your local fish store, while others argue the best place to purchase your aquarium salt is from the place that offers the lowest price–after all, salt is a commodity. Others argue in favor of convenience, preferring to buy their salt from the place that is most convenient to them.

Buy local or buy online?

In the end, deciding where to spend your hard-earned dollars is a personal choice. Your local fish store carries a lot of overhead–the cost of the building, the tanks, electricity to run everything and then, of course, all the shipping costs–so it will be difficult for them to be as price competitive. So if you’re inclined to support your local fish store, you may have to pay a little bit more.

If, however, you’re inclined to shop around and get the best deal for your money, you may be surprised to see that the online suppliers have become pretty competitive with the brick and mortar shops. Shipping reef salt mixes from online suppliers used to be cost prohibitive.

Sure, the reef salt mix might have been a buck or two cheaper, but you would get slammed with shipping costs due to the weight of the salt that would make the online transaction cost more than. But that’s not the case anymore.

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

I used to drive a pretty long way to get my salt. There is an awesome aquarium store located about 2o minutes from my parents’ house, and they had the cheapest prices around on aquarium salt for a reef tank. So I would plan a visit to the family and then swing by the old fish store on the way home. But as my own family has grown, the trip has become a bit of a chore. It can be tough to manage three kids under the age of 8 while carrying around a 50-pound bucket of salt (or two).

During the trip home, there is always the part where I accelerate, turn or stop too quickly and the bucket tips over…only to roll back and forth thumping around in the trunk for the whole trip.

Not to be overly dramatic here, because this is clearly a first-world problem, but I always found it stressful to know that this very heavy bucket of salt is rolling around in the car, directly behind my kids.

The trip to the local fish store is fun, but I was ready for a change.

One day, I was shopping online, when I found that Amazon was offering some pretty good deals on salt. The price is set by stores selling salt through Amazon, so the price fluctuates, but you can score some very good deals there.

 Shopping online

For the last two years, I’ve been buying my salt from Amazon.com! (disclosure that is an affiliate link). Unfortunately, the price has gone up a bit since I bought those last three buckets, but they still have pretty good pricing.

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. Right now, Amazon is selling a 200 gallon box of Instant Ocean sea salt for $40. 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…).

The thing I love most about buying my salt on Amazon is the free shipping I get on the salt + whatever else I buy there.

They really make it so easy to spend money there.

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.

So what is the best reef salt mix?

For me, the best reef salt mix 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 aquarium salt mix review of the best aquarium salt mixes, you may want to explore a few of the individual manufacturer sites for more information:

Are you brand new to the saltwater aquarium hobby?

Making your own aquarium saltwater from any of the best aquarium salt brands listed above is very easy. You can find step-by-step instructions on how to mix your own aquarium salt water here.

If you want to learn more about the most important reef aquarium water parameters, you can find more information here.

When making your own reef aquarium salt water, you want to carefully measure out the amount of salt mix and measure the specific gravity with a swing-arm hydrometer or a refractometer.

About the Author

How about you–what do you think is the best reef salt mix and why?