A refractometer is a field or laboratory machine designed to measure refractometry or the index of refraction. In turn, this index is calculated from the material composition using several mixing rules such as the Lorentz-Lorenz Equation and the Gladstone-Dale Relation or using Snell’s Law.
When it comes to measuring the salinity or salt content of water in an aquarium, you can either use the precise conductivity method or get a good reading through a handheld refractometer that measures the bending or the change of direction of the light as it passes from the air to the water. In water, light moves slower than in air and your refractometer can measure salinity by how slow light moves in saltwater.
Reviews of The Best Refractometers for Saltwater Aquariums
Here are the best refractometers in Amazon.com that money can buy for use in saltwater aquariums.
1. Ade Advanced Optics Salinity Refractometer:
This refractometer includes features like the specific gravity of 1.0 to 1.07 0 to 100 PPT of Salinity. It’s also designed to be sturdy thanks to its compact design and lightness in weight. You can carry it around everywhere with the portability of a cellphone.
Its readings are assuredly accurate through its ATC or Automatic Temperature Compensation and the device itself is made of aircraft-grade aluminum. It gets decent user ratings because it can be used for things like saltwater aquariums and tide pools in the intertidal zone.
2. DD Aquarium Solutions ATC Seawater Refractometer:
DD Aquarium Solutions share the same benefits as Ade Advanced Optics in terms of mobility and durability. However, it has different specs and even different features that make it stand out, like the fact that it’s specifically made for use in saltwater aquariums and doesn’t have as many side applications.
According to some users, the DD Aquarium Solutions ATC Seawater Refractometer is a highly recommended unit by saltwater aquarium owners, saltwater hobbyists, and coral botanists, but mostly the first one. Unlike other units, it has a sturdy feel to it that assures its precision won’t be affected by the wear-and-tear or accidental damage. It also takes only 20 seconds to calibrate the device.
3. Amzdeal Salinity Refractometer:
This highly rated salinity measurement device is a handheld refractometer with automatic temperature compensation, which means it can be used with temperatures ranging from 5 to 30°C or 41 to 86°F. The easy-to-use device can be calibrated using distilled water and even has a dual salinity scale.
This means it’s more precise since it measures salt content and salt specific gravity. It’s a complete package as well, since it comes with all accessories (this includes the user manual, storage case, cleaning cloth, screwdriver, and dropper). Some users claim it looks cheap compared to the more heavy-duty aluminum refractometers, but it nevertheless works excellently.
4. AquaticHI Aquarium Refractometer:
This highly rated but not as well-known refractometer also measures both salinity and specific gravity for better accuracy like Amzdeal. However, it has specs better suited for a variety of applications, unlike DD Aquarium Solutions.
It’s also versatile because you can use it for all sorts of purposes on top of aquarium maintenance like biology projects, gardening, education, agricultural, and marine monitoring. Among the collection of refractometers on this list, this one is the most multipurpose of the lot. It even includes a hard carrying case, spare plat prism, batteries, instruction manual, cleaning cloth, 3 pippet, and a calibrating screwdriver.
5. Ade Advanced Optics Automatic Temperature Compensation:
This particular refractometer only requires 2 to 3 drops of solution in order to track aquarium salinity. It also features all-metal construction, which naturally makes it superior to “cheaply” made refractometers like Amzdeal Salinity Refractometer.
It also features a premium optical lens, an easy-to-read scale, repeatable and precise measurements, a simple focus adjustment with its prism and lens construction, and it comes complete with equipment like a plastic pipette, calibration screwdriver, and case. Alas, it doesn’t have as many accessories included as Aquatic HI and Amzdeal.
The Main Refractometer Benefits of Note
Salinity is the next most important measurement of seawater you can make for your aquarium, with the temperature being the number one concern. Both low-salt and high-salt environments make unsuitable living conditions for fish in your fish tank. Therefore, you should be able to stabilize salinity by keeping tabs on it then fixing it when salt levels rise.
With that in mind, here are the main benefits you should be on the lookout for when shopping for a refractometer.
Easy Calibration: All refractometers can be calibrated. Using a screwdriver, adjust the indicator. This confirms the freshwater is at zero. This is the reason why different meters might differ in specific gravity and salinity. When buying a refractometer, make sure it’s calibrated for seawater use instead of brine used. Incidentally, brine is a simple water and salt solution without the rest of the elements found in seawater.
Effortless Maintenance: The best refractometers are those that require only periodic calibration using calibration fluid or RODI water. They should practically be self-maintaining when push comes to shove. In addition, you don’t need to rinse the best ones after usage. Some of them include a microfiber cloth for drying out the prism. Therefore, you should avail of the meters with the microfiber cloth included in the package.
Accuracy: The most accurate refractometers are able to calculate salinity even in environments with low salt levels. They should also be easy to use so that human error will have little impact on the preciseness of the reading. You should be able to place 1-2 drops of aquarium water unto the prism glass to see how the sample water slows and bends the passing light. The tiny internal scale should then give you readings in regards to specific gravity and salinity. It should also include an eyepiece that allows you o easily view the readings.
The best refractometer effectively monitors your seawater aquarium’s salinity in an instant with dependable precision. The thing to look for when it comes to refractometers is a combination of affordability and accuracy, thus ensuring that your investment is cost-effective when all is said and done.
With that in mind, the Automatic Temperature Compensation 0-32% Brix Refractometer has gotten quite the positive feedback from its users because it works efficiently and requires only 2 to 3 drops of water to gauge seawater salinity with dependable accuracy. This handheld device also helps with CNC coolant maintenance, wine or beer makers, and testing fruits, vegetables, and grasses.