salt

What is the best reef salt mix? A comparison of top marine salt for the aquarium

The first time I walked through my local fish store to pick a salt mix for my tank, I was completely overwhelmed. There were pallets and pallets of different brand salt mixes. So I spent some time researching to find the best one and here is what I found.

The best reef salt mix will right blend of calcium, magnesium and trace elements in a precise ratio that will help you create the perfect environment for saltwater fish, corals and other invertebrates when properly mixed with freshwater. The industry standard is the Reef Crystals brand, by Instant Ocean. 

salt purification and collection
This is where salt comes from

See how the most popular brands stack up

To help decide which brand is actually the best, I started to compare the calcium, magnesium, and alkalinity levels, side by side. What’s the point of spending all that money on a salt mix, if I have to add a bunch of supplements just to get them into the right range.

As you can see from the chart below, the Reef Crystals Brand (which is what I use in my own tanks) stands out.

Image
Tropic Marin ATM10581 Pro Reef-Bucket for Aquarium, 200-Gallon
Instant Ocean Sea Salt for Marine Aquariums, Nitrate & Phosphate-Free, 200-Gallon
Best Reef Salt Mix
Instant Ocean Reef Crystals Reef Salt, Enriched Formulation for Aquariums, 200 gal
Red Sea Fish Pharm ARE11230 Coral Pro Marine Salt for Aquarium, 175-Gallon
Makes 200 gallons
Makes 200 gallons
Makes 200 gallons
Makes 175 gallons
Calcium
Calcium ~450 ppm
Calcium ~400 ppm
Calcium ~490 ppm
Calcium ~450 ppm
Alkalinity
Alkalinity ~8.5 dkh
Alkalinity ~11 dkh
Alkalinity ~13 dkh
Alkalinity ~12.2 dkh
Magnesium
Magnesium ~1230 ppm
Magnesium ~1350 ppm
Magnesium ~ 1440 ppm
Magnesium ~ 1340 ppm
Image
Tropic Marin ATM10581 Pro Reef-Bucket for Aquarium, 200-Gallon
Makes 200 gallons
Calcium
Calcium ~450 ppm
Alkalinity
Alkalinity ~8.5 dkh
Magnesium
Magnesium ~1230 ppm
Check out the price
Image
Instant Ocean Sea Salt for Marine Aquariums, Nitrate & Phosphate-Free, 200-Gallon
Makes 200 gallons
Calcium
Calcium ~400 ppm
Alkalinity
Alkalinity ~11 dkh
Magnesium
Magnesium ~1350 ppm
Check out the price
Best Reef Salt Mix
Image
Instant Ocean Reef Crystals Reef Salt, Enriched Formulation for Aquariums, 200 gal
Makes 200 gallons
Calcium
Calcium ~490 ppm
Alkalinity
Alkalinity ~13 dkh
Magnesium
Magnesium ~ 1440 ppm
Check out the price
Image
Red Sea Fish Pharm ARE11230 Coral Pro Marine Salt for Aquarium, 175-Gallon
Makes 175 gallons
Calcium
Calcium ~450 ppm
Alkalinity
Alkalinity ~12.2 dkh
Magnesium
Magnesium ~ 1340 ppm
Check out the price

For me, of all the salts on the market, the best reef salt mix is Reef Crystals, by Instant Ocean. I will dive deeper into the comparisons in the following paragraphs.

The three most important aspects of a reef salt mix

Let’s start with an objective comparison across three important water parameters:

  1. calcium
  2. alkalinity
  3. magnesium
Tropic Marin Pro Reef Salt Mix in a bucket
This is an ultra-premium brand with a loyal following

Calcium (Ca)

Calcium is a critically important component in ocean water (and the aquarium salt that we use to make that water). Ca is used by LPS corals like the Torch coral and other invertebrates in the tank to build their stony skeletons.

Calcium from periodic table of elements
Did you know the molecular weight of calcium? It’s in this image

A typically recommended calcium level 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 the water will be calcium.

So it goes without saying (I guess I just said it though), that you should look carefully at the calcium levels in your desired salt mix.

Any brand with a level of around 400 ppm is good/ suitable. Significantly lower should be a red flag. Significantly higher is probably a good thing.

If you select a bargain salt with a low level of calcium, you’re going to have to spend additional time and money supplementing the water to get your desired levels. The other perspective of that point is that a salt mix with high levels of Ca is that you may not need to supplement your water to maintain appropriately high levels in your tank.

Alkalinity (Alk)

The alkalinity of the mixture is another important feature to consider. Alk is also, unfortunately, a challenging concept to describe in simple terms. It’s a chemistry thing, related to the pH, or relative acidity of the water. Here is how it works. The scale is about comparing to ‘regular freshwater.

testing for alkalinity
Alkalinity is also sometimes called ‘hardness’, measured in dKh

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, especially for LPS corals like Acans, Hammers, Favia, or Elegance corals, as well as SPS corals like Birds Nests, Acropora and Montipora.

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

You would want to avoid a salt mix that makes your alkalinity too low or too high or is inconsistent between batches (which would cause the levels in your tank to swing back and forth.

reef salt mix comparison article
I took this picture of Instant Ocean salt mix myself…can you tell? Hahaha.

Magnesium (Mg)

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. Since magnesium is generally readily available in a high-quality salt mix, you just want to double-check and make sure that it is also abundant in the brand you choose…just so you know it is not something you generally need to worry about, in the best reef salt mix brands.

That doesn’t mean it isn’t important, just that you likely have it covered. Magnesium does become particularly important if you run into algae problems that you just can’t solve, like with Bryopsis, Hair algae or Cyanobacteria . Often times, those unsolvable problems are solved by raising the Magnesium.

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:

  1. Tropic Marin Salt Mix
  2. Instant Ocean Salt Mix
  3. Brightwell
  4. Red Sea Coral Pro
  5. Tropic Marin Pro Reef
  6. Reef Crystals Salt
  7. Kent Marine
  8. Seachem Reef Salt
  9. Coralife
best reef salt comparison chart number 1. Shows calcium, alkalinity and magnesium levels across brands
Look across these marine reef aquarium salt mixes to compare the levels of calcium, alkalinity, and magnesium compared with the recommended range

The reported values of calcium, alkalinity, and magnesium are listed in the reef salt comparison chart, for each brand and the recommended range/value is included at 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 best reef salt mix options 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 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 conclusions about these top brands

  1. I would feel comfortable purchasing and using 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 in calculating the cost (or cost savings) of one salt versus another.
Red sea coral pro salt mix
after using the salt, this bucket is great as a black round tub to raise fish larvae

Comparing the costs of the best reef salt mix options

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 salt water, 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 number 2. Shows cost per pound and cost per gallon for popular salt mixes
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.

Factoring in the cost of adding supplements to your water

It wouldn’t be right to rule out a particular brand, just because they have a naturally lower concentration of a key element, because it is possible that you could add a supplement to the water mixed with that particular brand and achieve superior levels, at a better price–if the price is right.

Of course, the opposite is true as well.

For example, 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).

orange and white reef crystals salt mix box
Comparing prices can be tricky, this size will make 200 gallons of water (a little less actually)

Those who 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.

salt crystals on a black table
This is not a reef tank salt mix, but the image is pretty cool

Why is Instant Ocean Reef Crystals salt mix the best?

Instant Ocean Salt is the best because it is a great quality product at a reasonable price. I realize that sounds straightforward, but that’s the type of person I am–and I put my money and my reef tank’s health where my mouth is.

Check out the prices on Amazon

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

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

I buy Instant Ocean Reef Crystals 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…).

which is the best reef salt mix

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.

Looking for more product review info like this?

If you found this article helpful in simplifying some of the noise out there about what you should buy, check out these other helpful articles:

What do you think?

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

[author title=”About the Author”]

the word salt written in salt by tracing the letters in the crystals on a black background


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Comments

8 responses to “What is the best reef salt mix? A comparison of top marine salt for the aquarium”

  1. Thomas Pierce

    Thank you Albert. I really enjoyed this article. I just wish there was more testing , even some consistent basic tests included instead of relying on sometimes exaggerated data supplied by their marketing department on the packaging.

    I have been in this hobby for over 15 years and I believed we still do not know everything. Regarding salt mix and which products are better, well for a start there will be new products promising some new miracle or extra elements just to ensure they will get more customers especially newcomers.

    For my coral (lps and sps) tank I had success using Red Sea Pro, Aquacraft MarineEnvironment and Reef Crystals. Good quality test kits are necessary to ensure basic elements are supplemented every now and then, as time goes by.

    The worst product was Aqua Forest Probiotics which caused bacteria bloom and unwanted parasites to thrive if not used soon after the mix has been completed. Although it mixed very fast, I decided the probiotics was no better than using a drop of cheap brown rice vitamins into their salt mix. I emailed to Aqua Forest and had no support other than a robotic response to contact your local supplier. My supplier told me he was powerless to do anything and instead recommended me to use Red Sea Pro or continue using MarineEnvironment!

    Another product that I avoid is Aqua Ocean Sps Premium. I had terrible inconsistencies using 3 bags of it. One bag had very high magnesium and the other had low magnesium and the other has deficiency in calcium.

    1. Hi Thomas, thanks for the comment and compliment. I’m glad you enjoyed the article. Thanks for sharing your experiences with those other salt brands. Agree with you that having more data with respect to testing would certainly help differentiate. Good points.

  2. Marcy

    Hi, I am so happy to have found you though not soon enough as would have gotten a tank with a sump ! I have subscribed several times without getting any response incl. spam filter, just wondering where the problem is… Read all your e books & use your journal. I was purchasing salt from LFS already prepared they used Reef Crystals but found I always had to add Alk, Ca & Mg & always had crud in the bottom of bottles so decided to mix my own & found that also to be problematic having to add more salt & minerals & still had the crud. Will try Instant Ocean. I keep SG @ 1.025 & use the Milwaukee meter as eyesight leaves a lot to be desired. Well hoping I get added to your list, love your sense of humor. Gratefully, Marcy

    1. Hi Marcy, I’m glad you found the site too. Sorry to hear about the challenges signing up. Not sure what the deal is. I’ll try to add you manually. Thanks for reading the books and using the journal!

  3. Conrad Noto

    Great article, I’ve tried every salt listed and few others over the past 10 years. The current craze seems to be Fritz , I tried some, nothing bad to say about it, but decided to stick with my favorites. Instant Ocean and Seachem. I am surprised to see Seachem discontinued after clicking link above. I am hoping the new Vibrant sea has same quality/price. I use Instant Ocean for fish only, but prefer Seachem reef for mixed tank/hard coral the main reason is I find it keeps ph higher and seems the ph is more stable and consistant batch to batch.

  4. Conrad, thanks for sharing your experiences. You’re right, it does seem like there are ‘hot’ brands that come and go–Fritz does have some buzz.

    I’m not quite sure about Seachem’s choice to discontinue–it will be interesting to see if the new brand (Vibrant sea) becomes popular.

  5. Danny D Weiss

    G’day Albert. I like to congratulate you on this fine article here. Not only it is very informative but also useful for newcomers too. We been in the aquarium business for more than 2 decades and if there is one thing that a lot of people ponders for the first time frequently is which salt to use and which is the best. All we can say is to use a known brand first and then venture to others later if necessary.
    There are quite a growing number of brands around all promising to be superior in something. However problems can arise when a person starts to modify by adding calcium or magnesium or others without accurate dosing.

    Today there seem to be synthetic formula types and evaporative salts mixes. One of the main problem in using evaporative sea salt is it depends on the currents in the ocean and seasons or if it was derived from desalination plants where maintenance program can have an effect. Regardless of the final blending process, it can affect some batches.
    This is one grey area where a lot of people are not aware when using solar evaporated salts especially for critical purposes other than general home cooking.

    Albert, have you tried other new marine salts lately?

    1. G’day Danny and thanks for the comment. I’m a big proponent of not changing things that are working well in this hobby. I’ve had problems, in the past, when switching aquarium salt brands (even when switching to a ‘superior’ brand).

      My tank is doing fine as is–so I still use Instant Ocean. If I was having problems, I would not hesitate to try something new, but in the absence of a reason, I’m not looking to change that up.

      Thanks for the comment–sounds like you’re in the salt business?

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