Best Salinity Refractometer – How to Use and Best Picks

Updated on January 15, 2021 by

This post includes affiliate links, for which we may earn a commission at no extra cost to you should you make a purchase using our links.
As an Amazon Associate, we earn from qualifying purchases. Learn more.

What Is a Salinity Refractometer?

Setting up a saltwater tank can be a hassle compared to freshwater ones. Adding to the challenge of maintaining optimal water quality and chemistry, the art of preserving the saltwater levels (salinity) could be tricky. If this is not adequately addressed, it might stress the fish or even worse – so that’s why we need to use the best salinity refractometer.

But not to worry much, we’ve got the right help for you. The saltwater levels can be measured by looking at the specific gravity of the amount of dissolved salt in the water.

Should you rather take a quick look at our top 3 best salinity refractometers here they are:

Top Handled Refractometer
Vee Gee Scientific STX
Vee Gee Scientific STX
9.7

Type: Handled
ATC: Yes
Measures: Salinity & Temperature

Best Digital Refractometer
MISCO AQUAR Palm
MISCO AQUAR Palm
9.5

Type: Handled
ATC: Yes
Measures: Salinity

Best Salinity Pen Tester
Hanna Salinity Tester
Hanna Salinity Tester
9.1

Type: Handled
ATC: No
Measures: Salinity & Temperature

What is the Optimal Salinity for Saltwater Tanks?

Unfortunately, many fish keepers experience difficulty maintaining the water’s salinity due to inaccurate specific gravity measurements and calculations within the optimal range of 1.023 to 1.025.

Therefore measuring the amount of dissolved salt in the water is a more accurate and useful method of determining salinity. The amount of dissolved salt in your tank can be accurately determined, monitored, and regulated with the help of the best salinity refractometer.

You might also be interested to check out our article on the best TDS meters for aquarium as well.

If this is your first time hearing that, sit tight, take a sip of coffee, and scroll along with me. You’d already feel like an expert user.

The word refractometer is coined from the word refraction, which means the bending of light as it passes through a medium.

Best Salinity Refractometers Compared

ImageProductFeaturesPrice
Best Handled Refractometer
Vee Gee Scientific STX-3
Vee Gee Scientific STX-3

Type: Handled
ATC: Yes
Measures: Salinity & Temperature

Check On Amazon
Best Budget Refractometer
AGC Salinity Refractometer
AGC Salinity Refractometer

Type: Handled
ATC: Yes
Measures: Salinity

Check On Amazon
Good Value Refractometer
AUTOUTLET Refractometer
AUTOUTLET Refractometer

Type: Handled
ATC: Yes
Measures: Salinity

Check On Amazon
Robust Salinity Refractometer
ATC Salinity Refractometer
ATC Salinity Refractometer

Type: Handled
ATC: Yes
Measures: Salinity

Check On Amazon
Best Digital Refractometer
Milwaukee Digital Salinity Refractometer
Milwaukee Digital Salinity Refractometer

Type: Digital
ATC: Yes
Measures: Salinity

Check On AmazonCheck MarineDepot
Most Accurate Refractometer
MISCO Digital Handheld Refractometer
MISCO Digital Handheld Refractometer

Type: Digital
ATC: Yes
Measures: Salinity

Check On Amazon
Best Salinity Pen Tester
Hanna Salinity Tester
Hanna Salinity Tester

Type: Digital Handled
ATC: No
Measures: Salinity & Temperature

Check On AmazonCheck MarineDepot
Easy to Use Refractometer
Salinity & Temp Meter Pen
Salinity & Temp Meter Pen

Type: Digital Handled
ATC: Yes
Measures: Salinity & Temperature

Check On Amazon
Fast Salinity Tester
ORAPXI Digital Salinity Tester
ORAPXI Digital Salinity Tester

Type: Digital Handled
ATC: Yes
Measures: Salinity & Temperature

Check On Amazon

How Does a Refractometer Measure Salinity?

Light bends at different angles as it passes through various mediums and refracts differently to varying degrees according to the amount of salt dissolved in the water. The best salinity refractometer measures this degree of refraction regarding the amount of dissolved salt in the water, allowing us to precisely measure the saltwater level (salinity) of the tank.

However, it is quite eluding that most aquarium refractometers are designed only to measure the amount of sodium chloride (NaCl) content, otherwise known as the simple salt. As much as this is the primary determining factor of water salinity, the saltwater fish’s seawater home contains some other minerals and elements such as calcium and magnesium.

These minerals and elements are essential to the fish and a contributing factor to the water’s salinity.

Sadly, most of these salinity refractometers are not designed to detect nor even measure the presence of these minerals and elements, resulting in an up to 5% error in determining the tank’s accurate salinity.

To test different water parameters, you might also be interested to check out our article on the best water test kits as well.

Therefore, to have the most accurate salinity measurement, which will also detect and measure the presence of these minerals and elements, I would suggest you instead go for a seawater refractometer rather than a saltwater refractometer.

There are different types of salinity refractometers for aquariums in the market, which are usually designed for purpose-specific usage, including brewery, urine, and wine, among many others. Therefore, you must make sure to go for the best salinity refractometer used to measure salinity and specifically give your fish the optimal salinity level.

The good news is that we’ve got you covered on that. For most seawater, the salinity is between 3.0%-3.5% or 30-35 parts per thousand (ppt), the conductivity of 53mS/cm, and the refractive index of 1.33940.

So this should be regarded as the optimal salinity of your saltwater tank.

What Are the Types of Salinity Refractometers?

In fish keeping, two broad types of refractometers are commonly used: handheld salinity refractometer (analog) and digital salinity refractometer.

Handheld Salinity Refractometer (Analog)

A handheld refractometer for aquariums is the cheapest and by far the most commonly used aquarium refractometer. While this may not be as accurate as digital refractometers, it can be suitable enough for most aquarists.

If you went for a handheld salinity refractometer, I would suggest you go for one with Automatic Temperature Compensation (ATC).

This will permit a more accurate reading as the temperature fluctuations would be accurately factored in the measurement.

Handled salinity refractometers (analog) display their reading in specific gravity (SG) and parts per thousand (ppt).

To measure the water’s salinity using a handheld refractometer, calibrate the refractometer, add a few drops of the water to the refractive prism, and then read off the measurement through the eyepiece.

Handled Salinity Refractometers PROs & CONs

PROs
  • Fairly cheap
  • Easily portable
  • Does not require batteries
CONs
  • Requires manual calibration
  • Subjective measurement
  • Cheaper products are less accurate
  • More efforts needed to use and read off measurements

Digital Salinity Refractometers

This is by far the most accurate and easy-to-use type of salinity refractometer when compared to the handled option.

The digital salinity refractometer measures the accurate salinity in a few seconds and displays the result on a clear and easy-to-read LCD screen.

However, a comfortable and accurate tool comes with a price tag; therefore, digital refractometers are more expensive than handheld refractometers.

Digital Salinity Refractometers PROs & CONs

PROs
  • Highly accurate
  • Easy to use and read off measurements
  • Quick and precise
CONs
  • Quite expensive
  • Requires a battery

In this article we review the best handled and digital salinity refractometers to give you the best marine fishkeeping experience.

1. Vee Gee Scientific STX – Best Handled Salinity Refractometer

Vee Gee Scientific STX-3

If you require a handheld refractometer for saltwater to give you the most accurate salinity reading, then the Vee Gee Scientific STX-3 Handheld Refractometer would be a superb device to consider.

This aquarium refractometer is a portable and water-resistant salinity refractometer with great design and functions.

It measures the salinity of different salt solutions, including sodium chloride, magnesium, and calcium sulfate in liquids.

The body comprises a high-quality metal composed of copper alloy and nickel-chrome coating and a rubber grip for comfortable grip and usage. The optical glass is made with a high-quality refractive index prism.

The analog Brix scale has a bright and high-contrast display for straightforward and easy reading. The readings are illuminated by ambient light and viewed through a monocular, focusable, cushioned eyepiece.

It displays an instantaneous result in a dual scale of specific gravity with a range of 1.000 – 1.070 and parts per thousand having a range of 0 – 100%. It is built with an Automatic Temperature Compensation function with an ambient temperature of 10-30 °C. The reef refractometer has a salinity accuracy of +/- 1.0% ppt and +/- 0.001 SG with +/- 1 oC temperature accuracy.

The package comes with a zippered vinyl carrying case, a plastic transfer pipette, and a user manual. This salinity tester for aquarium also comes with a one-year warranty, which can be very handy.

PROs
  • High-quality design
  • Improved optical glass function
  • Automatic Temperature Compensation function
  • Dual scale reading
  • Highly accurate, consistent, and holds calibration
CONs
  • Relatively expensive

2. AGC Salinity Refractometer – Top Budget Pick

Top Budget Pick Salinity Refractometer

If you need a pocket-friendly refractometer, then this could be one of the optimal products.

This is a multipurpose salinity refractometer with diverse use in marine environment monitoring, aquarium water monitoring, swimming pool water measuring, laboratory testing, and industrial services.

It is designed to display readings in two different scales simultaneously in one test, including specific gravity and ppt. It has a scale range of 0 – 100% (1% = 1ppt) and a specific gravity range of 1.000 – 1.070 to measure the least and highest possible salinity for most seawater fish.

This fish tank refractometer also has a minimum reading resolution of 1%, allowing it to measure even a low concentrated salt solution accurately.

It is also built with Automatic Temperature Compensation (ATC) that reduces the effect of temperature, which might affect the refractive index of the water and thus impede the accuracy of the salinity measurement.

This product package is equipped with a hard case, droppers, a screwdriver, a manual, and a cleaning cloth. All this coming at an attractive price.

To measure the salinity of your tank, calibrate the device by placing a few drops of distilled water on the prism and adjust the calibration screw to zero with the included screwdriver. Then place a few drops of the solution you wish to measure on the prism and view through the eyepiece to read the measurement.

PROs
  • Easy to use
  • No battery is needed
  • Automatic Temperature Compensation
  • Displays are reading in dual scale
  • Comes with all needed full kit
CONs
  • You need to buy calibration solution as well

3. AUTOUTLET Refractometer – Good Value Pick

AUTOUTLET Refractometer - Good Value Pick Refractometer

The AUTOULET Refractometer is another pocket-friendly dual scale refractometer used to measure, monitor, and regulate saltwater and tank salinity with purpose-specific use for an aquarium and marine monitoring.

As a dual scale device, it displays the reading in both specific gravity and parts per thousand with a density measurement range of 1.0 – 1.070 having a minimum scale of 0.001 and a parts per thousand concentration measurement range of 0 – 100% having a minimum scale of 1%.

You’ll be thrilled to find it’s built with an Automatic Temperature Compensation (ATC) of 0-10% °C and a reference temperature of 20 °C. It also has a measuring range of 0 – 10% salinity with 0.2% division salinity. Its accuracy measurement is pegged at +/- 0.2%.

The product package comes with all the necessary equipment for easy use, including one salt salinity tester, three plastic pipettes, one mini screwdriver, one user manual, and one cleaning cloth.

To measure salinity effectively we recommend the following steps:

  • Ensure that this device is set at the ambient temperature of 68 °F.
  • Calibrate with about three drops of distilled water.
  • Screw the crew driver to zero.
  • Clean the prism with the included soft cloth, place about 2-3 drops of the saltwater on the prism, and read the measurement through the eyepiece.
  • After use, ensure to clean and dry the device with a soft cloth before packaging it back.
PROs
  • Automatic Temperature Compensation (ATC)
  • Dual scale reading
  • Comes with a full kit
  • Fairly cheap
  • Easy to use
CONs
  • It might require frequent calibrations before use
  • Readings might sometimes be off the accuracy range

4. ATC Salinity Refractometer – Robust Salinity Refractometer

Robust Salinity Refractometer

This is yet another handled portable refractometer that would give you an excellent use for a reasonable charge.

It is specifically designed to measure the salinity of seawater and salt solutions with low concentrations.

It’s an ideal salinity refractometer for reefs, marine monitoring, agricultural, gardening, and educational purposes as well.

It is also a dual scale salinity refractometer that displays the readings in both specific gravity and parts per thousand simultaneously.

This refractometer for the saltwater aquarium has a superior quality design with the body made of aluminum alloy and the optical system made with a high-quality refractive index with smooth focus.

The salinity refractometer is resistant to abrasion and corrosion, which makes it suitable to measure corrosive liquids. But this is not recommended for a long time, and the residue should be cleaned adequately after usage.

It has an Automatic Temperature Compensation (ATC) function that accurately measures reef tanks’ salinity with temperature changes. It also comes with all the necessary full kit and a manual to guide you on calibrating and using the reef refractometer efficiently.

With about 2-3 drops of the solution, accurate readings can be measured in a few seconds. It comes with an exciting full 12 months replacement warranty.

PROs
  • Automatic Temperature Compensation(ATC) function
  • High-quality design
  • Dual salinity scale
  • Full 12 months replacement warranty
  • Relative high accuracy and consistency
CONs
  • Calibration might be slightly off

5. Milwaukee – Best Digital Salinity Refractometer

Milwaukee MA887 - Best Digital Salinity Refractometer

Milwaukee MA887 Digital Refractometer is a professional salinity meter that’s just awesome to check salinity levels in your reef tank regularly.

This digital salinity refractometer is a multipurpose device for various applications, including domestic, laboratory, and industrial testing.

With a simple user calibration using distilled or deionized water, this device can measure salinity and give the most accurate reading. It is a 3-scale salinity meter, displaying salinity measurement in Practical Salinity Units (PSU), parts per thousand (ppt), or Specific Gravity (SG).

It has a PSU measurement range of 0 to 50 PSU, +/- 2 PSU accuracy, and 1 PSU resolution to give you a highly accurate reading within seconds.

It is built with automatic temperature compensation to resist the influence of temperature changes while measuring the salinity. We liked the yellow LED display screen that enables easy observation of the readings.

The digital salinity refractometer is powered with an included 9 V battery. It comes with distilled water for cleaning and calibration, a verification saline solution, two pipettes, and a user manual for practical use.

PROs
  • 3-scale display
  • Automatic Temperature Compensation (ATC)
  • Laboratory verified
  • Clear to read LED display
  • Easy calibration and use
  • Comes with a required full kit
CONs
  • It might require frequent calibrations

6. MISCO Digital – Most Accurate Refractometer

MISCO AQUAR-H2O Palm Abbe Digital - Most Accurate Refractometer

The Misco Aqua-H2O Palm Abbe digital handheld refractometer for aquarium is a professional salinity meter employed for many applications.

It can be also used with seawater, saltwater, and brackish water for oceanography, aquaculture, aquariums, desalination plants, and ocean research.

Regarding the seawater, this salinity tester for aquariums has an element detector array that detects and measures other minerals and constituent elements that affect the water’s salinity. It displays the salinity reading in “Practical salinity unit” and “Specific gravity”.

The readings are displayed on a large 24-character LCD screen with a display backlight. The aquarium refractor is easy to use with a one-button function to collect readings and one button to navigate the menu.

It is programmed with an automatic calibration function that automatically calibrates itself to water and automatic temperature compensation (ATC) that allows it to resist temperature fluctuations.

It is a very high precision salinity tester for aquariums with readings of about +/- 0.0005.

We found the protective rubber armor jacket and instructions manual quite useful.

PROs
  • High precision and accuracy
  • Large LCD screen with backlight
  • Equipped with an element detector array
  • Portable and easy to use
  • Automatic calibration and ATC
  • Dual scale reading in PSU and SG
CONs
  • Quite expensive, but never fails to accurately measure salinity levels

7. Hanna Salinity Tester – Best Salinity Pen Tester

Hanna Salinity Tester - Best Salinity Pen Tester

This is by far one of the best pocket-friendly digital salinity refractometers to give you an exciting fishkeeping experience.

It is made of a high-quality waterproof material, which allows it to float easily.

This digital salinity refractometer displays the reading in multiple scales including, parts per thousand (ppt), specific gravity (SG), and practical salinity unit (PSU).

The salinity readings are performed by an amperometric graphite probe that is efficient at resisting oxidation and reducing the polarization effect, thus producing accurate, repeatable measurement.

We recommend you to calibrate the device monthly with new calibration standards. The salinity tester should be rinsed with purified water and dried off with soft tissue before calibrating. It also has an automatic calibration function that automatically recognizes the 35 ppt standard calibration solution in calibration mode.

The aquarium refractometer also comes with four salinity calibration fluid packets. This digital salinity refractometer is more than you can ask for at a fair price.

PROs
  • High-quality waterproof body
  • Triple scale measurement
  • Automatic calibration
  • Comes with four salinity calibration fluid packs
  • Amperometric graphite probe for efficient reading
CONs
  • Calibrations might be slightly off

8. Salinity & Temp Meter Pen – Easy to Use Refractometer

Easy to Use Refractometer

This is an ideal salinity meter for marine aquariums and reef tanks use. It is a dual-purpose waterproof saltwater refractometer that measures both salinity and temperature.

It has a three scale measurement for salinity, including parts per thousand (ppt), %, and specific gravity (SG). The temperature is done on a dual scale of °C and °F.

With the touch of a button, one can easily switch between different units for different measuring purposes. It also has an in-built automatic temperature compensation function for accurate measurement.

The three scale measurement unit, including ppm, %, and SG, is displayed on a 30 x 18mm LCD screen.

The measuring range of salinity between 10-100 ppt, 0.0%-10.0%, and 0.950-1.080 SG. It has a portable and sleek pen-type design that makes it easy to use and easily carry about. It is built with an auto-ranging function, which allows the device to automatically determine and select a range to give you the best resolution and accuracy.

It has a built-in NaCl conductivity to TDS conversion factor, and this aquarium refractometer is powered with an included 4 LR44 button batteries.

PROs
  • Sleek design
  • Easy to use
  • Three scale measurement
  • Dual-purpose function
CONs
  • Not pre-calibrated
  • Readings might be off

9. ORAPXI Digital – Fast Salinity & TDS Tester

Digital Salinity Tester for Salt Water - 9. ORAPXI Digital -

This is a multi-function salinity refractometer that will never disappoint you.

Orapxi is designed to give you a satisfactory result in a wide range of uses, including saltwater, swimming pool, aquarium, and seawater.

In addition to the salinity measurement, this device can also accurately measure temperature, Total Dissolved Solids (TDS), and Electric Conductivity (EC).

It is built with a sensitive electrode sensor that ensures an optimum and quick measurement of a liquid’s salt content. The salinity measurement ranges within 0-9999ppm, 10-200ppt or 0-25%. You’ll see the results displayed on a clear-to-read green backlit LCD screen for easy observation.

It has a 2% salinity accuracy and a full scale of +/- 1 digit. The salinity resolution is about 0.01 ppt or 0.1 ppt. It is designed with an automatic temperature compensation function within the range of 32 °F to 140 °F.

The Orapxi salinity tester for aquarium is insured with a 30-day free return/replacement policy.

PROs
  • Fast and accurate
  • 4-in-1 salinity tester function
  • Backlit LCD screen for easy observation
  • Sensitive electrode sensor
  • After sales-free return/replacement policy
CONs
  • The device might not be pre-calibrated

To Conclude: What’s the Best Salinity Refractometer?

Salinity level remains a paramount factor to give your saltwater fish a befitting home in your aquarium tank. If this parameter is not adequately taken care of, your fish can often be stressed out or even die in extreme cases.

To observe, regulate, and maintain our tanks’ salinity levels, we have to make sure we picked and best salinity refractometer.

From our carefully selected reviews, you can equip yourself with the best refractometer of your choice to suit your needs and give your fish and reef the best home.

For the best handled refractometer for aquariums, we found the Vee Gee Scientific STX-3 the best candidate with the highest accuracy and usability.

For the best digital refractometer for aquariums, both Milwaukee and Misco are top-notch salinity refractometers. They differ, however, in terms of price tags, the former being more expensive.

In our list of best refractometers for a saltwater aquarium, you can find great picks from pocket friendly to most accurate handheld refractometers, but also highly accurate digital refractometers.