Aquarium Hydrometers

Best Deals
Aquarium Hydrometers
1
AUTOUTLET Salinity Refractometer Saltwater Aquarium for Seawater, Pool, Tank, Marine, Fishkeeping, 0-100PPT & 1.000-1.070 Salinity Tester with ATC Function Salinity Hydrometer Kit
AUTOUTLET Salinity Refractometer Saltwater Aquarium for Seawater, Pool, Tank, Marine, Fishkeeping, 0-100PPT & 1.000-1.070 Salinity Tester with ATC Function...
10
Amazon.com
2
Salinity Refractometer for Aquarium Seawater Marine Fishkeeping Salinity Tester 0-100PPT & 1.000-1.070 Salinity Hydrometer Slatwater Refractometer with Automatic Temperature Compensation (ATC)
Salinity Refractometer for Aquarium Seawater Marine Fishkeeping Salinity Tester 0-100PPT & 1.000-1.070 Salinity Hydrometer Slatwater Refractometer with...
10
Amazon.com
3
Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automatic Temperature Compensation
Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automatic Temperature Compensation
10
Amazon.com
4
Glass Aquarium Hydrometer with Built-in Thermometer Marine Floating Salt Water Salinity Tester 1.000-1.060 7.87in
Glass Aquarium Hydrometer with Built-in Thermometer Marine Floating Salt Water Salinity Tester 1.000-1.060 7.87in
8.8
Amazon.com
5
Aquarium pH Salt Tester, Digital Salinity Meter for Freshwater & Saltwater Fish Tank, Simultaneous display Salt pH TDS for Koi Pond, Reef Tank, Aquaponics PPM pH EC Reader, Hydrometer with S.G. Card
Aquarium pH Salt Tester, Digital Salinity Meter for Freshwater & Saltwater Fish Tank, Simultaneous display Salt pH TDS for Koi Pond, Reef Tank, Aquaponics...
8.8
Amazon.com
6
boxtech Aquarium Marine Test, Sea Saltwater Hydrometer, Reef Ocean Hydrometer Salinity Meter for Pool Aquarium Water Salinity Specific Gravity Test
boxtech Aquarium Marine Test, Sea Saltwater Hydrometer, Reef Ocean Hydrometer Salinity Meter for Pool Aquarium Water Salinity Specific Gravity Test
8.8
Amazon.com
7
Fluval Sea Hydrometer for Aquarium, Medium
Fluval Sea Hydrometer for Aquarium, Medium
8.8
Amazon.com
8
Coralife Aquarium Fish Tank Deep Six Hydrometer For Measuring Water Salinity PPT and Specific Gravity
Coralife Aquarium Fish Tank Deep Six Hydrometer For Measuring Water Salinity PPT and Specific Gravity
8.8
Amazon.com
9
balacoo Sea Water Densitometer Brine Hydrometer High Precision Salinity Hydrometer Densitometer for Aquarium, Saturated Fish Tank, in Both Fahrenheit Celsius
balacoo Sea Water Densitometer Brine Hydrometer High Precision Salinity Hydrometer Densitometer for Aquarium, Saturated Fish Tank, in Both Fahrenheit Celsius
7.4
Amazon.com
Aquarium pH Salt Tester, Digital Salinity Meter for Freshwater & Saltwater Fish Tank, Simultaneous display Salt pH TDS for Koi Pond, Reef Tank, Aquaponics PPM pH EC Reader, Hydrometer with S.G. Card
Aquarium pH Salt Tester, Digital Salinity Meter for Freshwater & Saltwater Fish Tank, Simultaneous display Salt pH TDS for Koi Pond, Reef Tank, Aquaponics...
4.0
$39.99
$21.99
Amazon.com
boxtech Aquarium Marine Test, Sea Saltwater Hydrometer, Reef Ocean Hydrometer Salinity Meter for Pool Aquarium Water Salinity Specific Gravity Test
boxtech Aquarium Marine Test, Sea Saltwater Hydrometer, Reef Ocean Hydrometer Salinity Meter for Pool Aquarium Water Salinity Specific Gravity Test
4.0
$15.99
$9.99
Amazon.com
Fluval Sea Hydrometer for Aquarium, Medium
Fluval Sea Hydrometer for Aquarium, Medium
4.0
$11.49
$9.09
Amazon.com
Coralife Aquarium Fish Tank Deep Six Hydrometer For Measuring Water Salinity PPT and Specific Gravity
Coralife Aquarium Fish Tank Deep Six Hydrometer For Measuring Water Salinity PPT and Specific Gravity
4.0
$15.78
$13.97
Amazon.com
Glass Aquarium Hydrometer with Built-in Thermometer Marine Floating Salt Water Salinity Tester 1.000-1.060 7.87in
Glass Aquarium Hydrometer with Built-in Thermometer Marine Floating Salt Water Salinity Tester 1.000-1.060 7.87in
4.0
$3.99
Amazon.com
balacoo Sea Water Densitometer Brine Hydrometer High Precision Salinity Hydrometer Densitometer for Aquarium, Saturated Fish Tank, in Both Fahrenheit Celsius
balacoo Sea Water Densitometer Brine Hydrometer High Precision Salinity Hydrometer Densitometer for Aquarium, Saturated Fish Tank, in Both Fahrenheit Celsius
3.0
$23.89
Amazon.com
AUTOUTLET Salinity Refractometer Saltwater Aquarium for Seawater, Pool, Tank, Marine, Fishkeeping, 0-100PPT & 1.000-1.070 Salinity Tester with ATC Function Salinity Hydrometer Kit
AUTOUTLET Salinity Refractometer Saltwater Aquarium for Seawater, Pool, Tank, Marine, Fishkeeping, 0-100PPT & 1.000-1.070 Salinity Tester with ATC Function...
5.0
$16.99
Amazon.com
Salinity Refractometer for Aquarium Seawater Marine Fishkeeping Salinity Tester 0-100PPT & 1.000-1.070 Salinity Hydrometer Slatwater Refractometer with Automatic Temperature Compensation (ATC)
Salinity Refractometer for Aquarium Seawater Marine Fishkeeping Salinity Tester 0-100PPT & 1.000-1.070 Salinity Hydrometer Slatwater Refractometer with...
5.0
$13.77
Amazon.com
Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automatic Temperature Compensation
Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automatic Temperature Compensation
5.0
$17.99
Amazon.com
Amazon price updated: October 9, 2025 3:45 pm
Glass Aquarium Hydrometer with Built-in Thermometer Marine Floating Salt Water Salinity Tester 1.000-1.060 7.87in
Glass Aquarium Hydrometer with Built-in Thermometer Marine Floating Salt Water Salinity Tester 1.000-1.060 7.87in
4.0
$3.99
Amazon.com
Fluval Sea Hydrometer for Aquarium, Medium
Fluval Sea Hydrometer for Aquarium, Medium
4.0
$11.49
$9.09
Amazon.com
boxtech Aquarium Marine Test, Sea Saltwater Hydrometer, Reef Ocean Hydrometer Salinity Meter for Pool Aquarium Water Salinity Specific Gravity Test
boxtech Aquarium Marine Test, Sea Saltwater Hydrometer, Reef Ocean Hydrometer Salinity Meter for Pool Aquarium Water Salinity Specific Gravity Test
4.0
$15.99
$9.99
Amazon.com
Salinity Refractometer for Aquarium Seawater Marine Fishkeeping Salinity Tester 0-100PPT & 1.000-1.070 Salinity Hydrometer Slatwater Refractometer with Automatic Temperature Compensation (ATC)
Salinity Refractometer for Aquarium Seawater Marine Fishkeeping Salinity Tester 0-100PPT & 1.000-1.070 Salinity Hydrometer Slatwater Refractometer with...
5.0
$13.77
Amazon.com
Coralife Aquarium Fish Tank Deep Six Hydrometer For Measuring Water Salinity PPT and Specific Gravity
Coralife Aquarium Fish Tank Deep Six Hydrometer For Measuring Water Salinity PPT and Specific Gravity
4.0
$15.78
$13.97
Amazon.com
AUTOUTLET Salinity Refractometer Saltwater Aquarium for Seawater, Pool, Tank, Marine, Fishkeeping, 0-100PPT & 1.000-1.070 Salinity Tester with ATC Function Salinity Hydrometer Kit
AUTOUTLET Salinity Refractometer Saltwater Aquarium for Seawater, Pool, Tank, Marine, Fishkeeping, 0-100PPT & 1.000-1.070 Salinity Tester with ATC Function...
5.0
$16.99
Amazon.com
Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automatic Temperature Compensation
Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automatic Temperature Compensation
5.0
$17.99
Amazon.com
Aquarium pH Salt Tester, Digital Salinity Meter for Freshwater & Saltwater Fish Tank, Simultaneous display Salt pH TDS for Koi Pond, Reef Tank, Aquaponics PPM pH EC Reader, Hydrometer with S.G. Card
Aquarium pH Salt Tester, Digital Salinity Meter for Freshwater & Saltwater Fish Tank, Simultaneous display Salt pH TDS for Koi Pond, Reef Tank, Aquaponics...
4.0
$39.99
$21.99
Amazon.com
balacoo Sea Water Densitometer Brine Hydrometer High Precision Salinity Hydrometer Densitometer for Aquarium, Saturated Fish Tank, in Both Fahrenheit Celsius
balacoo Sea Water Densitometer Brine Hydrometer High Precision Salinity Hydrometer Densitometer for Aquarium, Saturated Fish Tank, in Both Fahrenheit Celsius
3.0
$23.89
Amazon.com
Amazon price updated: October 9, 2025 3:45 pm

More information about Aquarium Hydrometers

Ensure the perfect environment for your aquatic friends with aquarium hydrometers. These handy tools accurately measure the salinity and specific gravity of your aquarium water, helping you maintain optimal conditions for your fish and coral. With a wide range of options available, from floating hydrometers to digital ones, you can easily find the one that suits your needs. Don't leave the health of your underwater ecosystem to chance – invest in an aquarium hydrometer today and keep your aquatic pets happy and thriving.

Questions about Aquarium Hydrometers

Aquarium hydrometers are essential tools for maintaining the ideal water conditions for your fish and marine life. They measure the specific gravity or salinity of the water, which is crucial for the health and well-being of your aquatic pets. By regularly monitoring the specific gravity, you can ensure that the water parameters are within the appropriate range for your fish and marine life. This helps to prevent stress, disease, and even death. For example, saltwater fish require a specific salinity level, and using a hydrometer allows you to adjust the salt content accordingly. Additionally, hydrometers help you monitor the effectiveness of any water treatment or filtration systems you have in place, ensuring that they are properly maintaining the desired water conditions.

When choosing an aquarium hydrometer for accurate readings, there are a few key features to consider. First and foremost, it's important to look for a hydrometer that is made from durable and high-quality materials. This will ensure that it can withstand the harsh conditions of the aquarium environment and provide accurate readings over time. Additionally, a hydrometer with a clear and easy-to-read scale is essential for accurate measurements. Look for one that has clear markings and a wide range of specific gravity measurements. Another important feature to consider is calibration. Some hydrometers come pre-calibrated, while others require manual calibration. It's always a good idea to choose a hydrometer that is easy to calibrate to ensure accurate readings.

Aquarium hydrometers can be used for both freshwater and saltwater tanks, but there are specific models designed for each type. The main difference lies in the measurement range and accuracy required for each type of water. For freshwater tanks, a basic hydrometer that measures specific gravity or salinity within a certain range will suffice. However, for saltwater tanks, it is recommended to use a more precise and accurate hydrometer that can measure salinity levels with greater precision. This is because maintaining the correct salinity level is crucial for the health and well-being of saltwater fish and invertebrates. Therefore, it is important to choose the appropriate hydrometer based on the type of aquarium you have.

While hydrometers are a commonly used tool to measure salinity and specific gravity in aquariums, there are alternative methods available that can provide accurate readings as well. One such method is the use of refractometers. Refractometers work by measuring the bending of light as it passes through a liquid, which can then be used to determine the salinity and specific gravity. They are known for their precision and are often considered more reliable than hydrometers. Another option is the use of digital salinity meters, which provide quick and accurate readings without the need for manual calibration. These meters use conductivity to measure the salinity of the water, making them a convenient and efficient choice for aquarium owners.

To ensure accurate readings and optimal water quality in an aquarium, it is recommended to calibrate or replace hydrometers regularly. The frequency of calibration or replacement depends on the type of hydrometer being used. For traditional glass hydrometers, it is advisable to calibrate them before each use to maintain accuracy. This can be done by comparing the readings with a known standard solution. On the other hand, digital hydrometers typically require less frequent calibration, usually every 3-6 months. It is important to follow the manufacturer's instructions for calibration and replacement to ensure accurate readings and maintain the health of the aquatic ecosystem.