Salinity is one of the most important indicators measured in a saltwater aquarium. Because it controls the balance of salt between the organism and its surroundings. Thus, reef aquarists may need a salinity refractometer to check the salinity of their saltwater aquarium. In this article, you will get to know how does a salinity refractometer work and how to measure refractometer salinity.

salinity refractometer

How does a salinity refractometer work

Monitoring salinity in marine aquariums is an important step in maintaining a stable environment for fish and corals. Refractometers are optical instruments used to measure the concentration of liquids. They can measure aquarium salinity, sugar content, moisture content, and coffee TDS.

A salinity refractometer is a test kit that accurately measures the salinity of marine aquariums. Light travels in a straight line. But when it passes through a medium such as glass or water, it changes direction or bends. The degree to which the light bends is according to the medium through which the light travels. Depending on the amount of salt dissolved in the water, the light will be refracted differently. Salinity refractometers can provide the aquarium water salinity by measuring the refractive index. You may also find the refractometer with a dual scale including specific gravity and parts per thousand.

salinity refractometer

Why do you need a refractometer for salinity measurement

It is important to have a clear understanding of the salinity levels of your aquarium water. Most reef aquarists used a glass hydrometer to measure the salinity levels in their reef tanks before. But now they want to have a refractometer for salinity measurement. Because it is more affordable and multi-functional.

Refractometers are also very accurate and easy to use for measuring concentrations. And they can be used for a long period without losing accuracy. A refractometer is an excellent tool for measuring the salinity of your reef aquarium. It will serve you well for many years if you use it carefully.

Unlike glass hydrometers, ATC refractometers come with the automatic temperature compensation ATC function. So, it allows a wider temperature range. And you don’t need to worry about the salt water temperature during measurements. As a result, many reef aquarists would like to use aquarium refractometers to measure the salinity of their reef aquarium.

To measure refractometer salinity, you need to know how to calibrate and how to use salinity refractometer first.

refractometer salinity

How to calibrate a salinity refractometer for seawater

Most salinity refractometers for aquarium use can measure sodium chloride solutions. The refractive index of sodium chloride solutions is different from that of seawater. Calibrating the refractometer also helps compensate for this difference. Here comes how to calibrate a salinity refractometer for seawater.

At first, open the cover of the test kit and wipe the prism with a soft cloth. This step is to ensure that there is no salt residue on the surface. Then, add a few drops of salinity calibration solution to the prism and close the cover. And wait about 50 seconds for the device to compensate for the temperature. Next, focus on the eyepiece with the prism turning towards a light source. Finally, read the salinity scale when the blue and white boundary lines coincide. If the reading does not correspond to the salinity calibration solution, make a small adjustment by the calibration screw.

As for digital refractometers designed for the measurement of seawater, the operation is much easier than these steps. Clean the test kit and add a few drops of calibration solution or distilled water. Then you will get digital salinity readings on the screen after a few seconds.

In most situations, the seawater refractometer calibration should be performed at room temperature. And you can also calibrate the salinity refractometer for seawater with distilled water. If calibrating the seawater refractometer with a salt water sample, you will get more accurate readings.

refractometer salinity

How to use salinity refractometer

Ensure that the refractometer is clean and dry before each use. After calibrating the refractometer, you need to know how to use salinity refractometer.

In the beginning, open the cover of the refractometer and wipe the prism with a soft cloth. Then, take a sample of water from your fish tank. And place the water sample on the prism. You’d better gently press the cover to distribute the water evenly.

Wait for the water to reach the temperature of the refractometer for several seconds. After that, look through the eyepiece of the tool. And read the salinity scale at the intersection of the blue and white lines. At last, wipe the prism with a soft cloth again.

But the steps for digital refractometers are much easier than these. Simply clean the tool and add a few drops of aquarium water sample from the fish tank. Next, wait for 15 seconds to take the digital salinity readings. You don’t need a calibration screw and a light source.

After measuring the aquarium salinity, protect your refractometer against dust and water. There are also some tips for reading salinity refractometers.

Tips for reading salinity refractometer

Ensure that the prism is free of dust or fingerprints. So, you can use a soft cloth to keep it clean. Do not use paper towels that may scratch the prism.

Rinse the device with water after measuring concentrations. Because any residual salt water will cause inaccurate measurements for next time use.

To get accurate measurements when reading salinity refractometer, you need to calibrate the refractometer monthly.

After adding the water sample, you’d better wait for a few seconds to let the temperature equilibrate. Then you will get more accurate salinity readings.

refractometer for salinity

Types of salinity refractometers

There are many types of refractometers on the market. They can work as a coffee refractometer, honey refractometer, maple syrup refractometer, etc. The two main types for measuring aquarium salinity are analog handheld refractometers and digital aquarium refractometers.

An analog handheld refractometer is the more affordable and commonly used aquarium refractometer. Besides, it doesn’t need batteries for measuring. Some handheld refractometers have dual scales including specific gravity and parts per thousand. But it may not be as accurate as digital seawater refractometers for its subjective measurements. And an analog hand held refractometer requires more effort to use. It needs manual calibrations and observations. Also, you must take the measurements with a bright light source.

A digital refractometer accurately measures the salinity in marine aquariums. It is easy to use and displays accurate salinity readings in a few seconds. And the readings are clearly displayed on the LCD screen. So you don’t have to interpret the results yourself. Besides, it comes with a single button calibration. Thus, the digital aquarium refractometer is easier for you to calibrate before use. Last but not least, you don’t need to take salinity measurements with a light source.

best salinity refractometer

Best digital refractometer for saltwater aquarium

Choosing the best salinity refractometer need to consider the proper measurement range first. Refractometers on the market designed for the measurement of seawater are ideal for aquarists to measure the salinity levels in their reef tanks.

The best digital refractometer for saltwater aquarium should also come with automatic temperature compensation ATC. This feature improves measurement accuracy by adjusting temperature changes. A digital refractometer for salinity is a quick and accurate tool for measuring the salinity of reef aquarium water. Once checked to be properly made, they usually can provide years of warranty service.

FJD best salinity refractometer contains a sensor for obtaining high-precision readings. Its small size and light weight make it portable to carry around. And the LCD display provides easy readings in any low light situation. Besides, it comes with automatic temperature compensation ATC to provide more accurate readings.

Also, this brix meter refractometer is IP67 rating water-resistant for easy cleaning. One integrated button allows for easy operation and simple calibration. And this tool comes with Bluetooth connectivity to your mobile phone with a wide range of measurement models. This best salinity refractometer requires a few drops of sample for micro-volume tests. Last but not least, each unit undergoes rigorous quality control to ensure its accuracy and performance.

FJD brix refractometer is the best digital refractometer for saltwater aquariums. It can measure a wide range of solutions with a 0-95% brix range. And the working temperature range is 5-45°C, meeting most needs of the measurements. Thus, if you want to buy a refractometer for salinity measurement, FJD digital refractometer is an ideal choice.