ESV B-Ionic Seawater Salt mix

E.S.V. B-Ionic Seawater System Review

When shopping for salt mix, ESV B-Ionic Seawater system is not one of the more common products marketed, however ESV has a long history in the salt water and reef tank industry. They are probably best known for their B-Ionic 2 part calcium buffer, which this salt mix is heavily based on.

Why B-Ionic Seawater?

I started this tank on a name brand salt which I have used over the years, and it performed as I expected, but the tank was mostly LPS and soft corals at the time. Once i made decided to add Montipora and other SPS corals, I started looking into some other salt options. I had read great things about quite a few brands, and eventually narrowed it down to just a couple choices, ESV and Aqua Forest, both were in the same price range and the reviews on popular reefing forums were similar.

Ultimately my previous experience with ESV and a bit of brand loyalty swayed my decision, I had used their calcium buffer 2-part over the years and had great results from it, so I expected good things from their salt too, although I was honestly a little hesitant about the idea of a 4 part salt mix.

What’s included:

The mixture comes in either a box or bucket, depending on the amount/size you need. Once you open the packaging you will find the 4 parts of the mix (Sodium, Magnesium, and the 2 bottles of liquid trace elements), there is also a set of plastic scoops for measuring the powder components, a measuring cup for the liquids, and the instructions.

The instructions give you the amounts to mix in both volume and weight, although they recommend using the weight method to achieve a mix more accurate to their stated parameters, and a more consistent mix. I purchased a kitchen scale off amazon for around $20 to measure out the correct amounts by weight and have seen consistent results.


I always start off with a fresh batch of RODI water, typically I’ll mix 15 gallons at a time since my tank is about 135 gallons, and I also perform water changes weekly.

The process of mixing is pretty straight forward, once you know how much water you wish to make, you start with about 1 gallon shy of the total. So if your goal is to make 15 gallons, it is recommended to start with 14 gallons of water.

You then add the Sodium Chloride and stir it until completely dissolved, then the Magnesium Sulfate gets mixed in and stirred until dissolved.

Once the two dry ingredients are mixed and dissolved, you move on to the liquid components.

Measure these out in the supplied measuring cup, add component one and mix it thoroughly, then do the same with component 2.

I typically give this mixture about an hour, then I test the specific gravity. Since I started with 1 gallon less than my desired total, the SG is almost always higher than 1.025.

I then add additional RODI to this mix until the SG is at my desired level for my tank, usually it takes the additional gallon of water to get to this reading.


ESV Seawater mixing instructions
ESV Seawater mixing instructions

The images below are from my most recent mix of 20 gallons.

I use a spare plastic cup, tare the scale, and then add the component.

Once the weight is correct, it gets mixed into the RODI.

My overall impression

Given that I initially expected a 4 part mix to be difficult to work with, it is actually quite simple. There is a little extra time involved in preparing the mix, but in this hobby nothing is ever fast. ESV B-Ionic Seawater is really clean and it leaves no residue in the mixing container. The mix dissolves quickly, and I am seeing really obvious growth from all my coral (Monti, SPS, LPS).

The Parameters of my mixed water came out to the exact numbers specified on the product label:

SG: 1.025

dKH: 9

Calcium: 450

Magnesium: 1400


  • Mixes cleanly, no residue left behind
  • Dissolves quickly
  • Consistent parameters
  • Seeing improved growth in SPS and Mintipora compared to the previous brand
  • Good customer service, I contacted them on Facebook and they offered to replace missing components due to ripped bags


  • 4 part mix requires a little extra time
  • All components are crammed into a 5 gallon bucket, resulting in small tears in the sodium bag, leaking into the bucket (see update below)
  • I needed to purchase a kitchen grade measuring scale to see real consistency in the parameters from batch to batch
    • mixing via the volume method rather than weight, was a little inaccurate
10/21/17 Update

I posted a review of the product on the ESV Facebook page, noting the ripped bags of salt. I received a response that they are now utilizing thicker plastic bags, so I will see if this fixes the problem in my next order. They also offered to replace any leaked, or shortage of components.



What makes B-Ionic Seawater different?

According to the ESV website, their salt mix is one of the Purest and most consistent mixes available

“Our B-Ionic Seawater System is a unique four-part system for mixing the purest, most consistent synthetic seawater available to the marine aquarist.

It is recognized that most reagent grade salts can contain contaminants (trace metals, etc.) at levels which may inhibit the growth of some algae species from low nutrient environments (oligotrophic) such as coral reefs. We address this issue by providing ultra-low heavy metal Sodium Chloride (maximum allowable lead concentration; lower than half the maximum allowable for reagent grade sodium chloride) and USP grade Magnesium Sulfate as the dry components of the system.

All other chemicals pre-dissolved in our liquid components are subject to our three phase purification process, resulting in significant lowering of contaminants, including phosphate. The many dry blends that are available on the market today may not be homogeneous, which can result in considerable chemical variations, not only from batch to batch, but also from within the same container. Furthermore, humidity contamination during storage can result in localized precipitation reactions.

The B-Ionic Seawater System avoids these issues by providing the dry components of our formulation in separate containers. All other major, minor, and trace elements are pre-dissolved in a highly concentrated two component liquid system. These components can then be easily measured for any size batch of synthetic seawater. Because we provide all of the slower dissolving ingredients in our liquid components, Batches mix quickly, and can be used within 10 minutes of preparation with no adverse effects, providing the initial RO and/or DI water contains sufficient dissolved oxygen.”

Future testing

I am going to keep a running list below of the parameters for each batch I mix up to determine the consistency. The parameters are measured with Salifert test kits so the results should be fairly accurate every time.

If you’d like to try this mix for yourself, you can get it at the link below. Where I live in Colorado, none of the local stores carry it.

Buy it Here 

Buy ESV Salt Mix

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