10 Best Hydrometer For Aquariums of August 2025

• Ensures proper gravity of aquarium water. Easy to use.
• Ensures all water has the same salinity within aquarium
• Green indicators are ideal range of water temperature and specific gravity for most salt water / marine aquariums.
• Measure both Temperature and Specific Gravity of the water.
• SIZE：19.2CM(7.5"). Glass Hydrometer; Measures Celsius and Fahrenheit

Aquarium Equip

• Included components: All Components included in Picture and Description
• Cora life is one of the markets leading manufacturers of premium aquarium products
• Cora life's Hydrometer takes a true water sample at six inch depth
• Easy to read and accurate, this specific gravity meter is designed to give temperature-corrected readings in warm water aquariums
• Coralife is one of the market’s leading manufacturers of premium aquarium products
• Coralife's Hydrometer takes a true water sample at six inch depth

Coralife

• No-wet-hands-design

MarineLand

• Measure salt water or salinity of water, ideal for aquariums and marine monitoring.
• Measures on 2 scales, Specific Gravity (D 20/20) and parts per thousand.
• Features automatic temperature compensation.
• Comes with hard case, dropper, screwdriver, user manual and cleaning cloth.
• The main part is made of chromium, it's very durable.

Agriculture Solutions

• 🐠 Safe Material & Unique Design: Made of durable Acrylic, this Fish Tank Test Kit salinity Hydrometer is designed with an automatic level function.
• 🐠 Quickly, easily, and accurately measurement: With this hydrometer saltwater aquarium test kit, you can test your marine aquarium's salt level and specific gravity, and It is optimum to be put into below 6" deep water to avoid the error caused by the oil film on the water.
• 🐠 Higher Accuracy & safe zone indicated: Readings are temperature-corrected & accurate to +/- 0. 001. specific gravity units ranges from 1. 000 - 1. 030 with a safe zone of 1.020-1.023. The outside range of scale indicates salinity ppt, ranges from 0-40, safe zone is 27-31.
• 🐠Easy to Read & Clean: The easy-to-read swing-arm pointer and extra wide stable base provide an accurate test result. After use, soak this saltwater meter in mild acid(vinegar) for 30 minutes, rinse with tap water and air dry. Do not disassemble.
• 🐠 Wide Usage:Fit for brackish and reef salt marine aquariums. Perfect for testing both salinity and specific gravity of your brackish and marine tank.Includes salinity and specific gravity scales.Suitable for fresh water and sea water.

capetsma

• 【Salinity Refractometer】Measure Salt Water or Salinity of Water,Monitor and Control the Concentration of Salt Water and Brine,Ideal for Aquariums and Marine Applications.
• 【Measures on 2 Scales】Specific Gravity (D 20/20) and parts per thousand and replaces your poor quality and difficult to read hydrometer.
• 【Density Measurement Range】1.0-1.070, Minimum Scale is 0.001.
• 【Concentration Measurement Range】0-100‰, Minimum Scale is 1‰.
• 【ATC】Automatic Temperature Compensation, 0-10°C.

AUTOUTLET

• Made of high quality plastic, aquarium transparent, automatic accurate reading brine hydrometer
• Accurate, durable and easy to read salt and specific gravity of your marine aquarium, small and waterproof. If the specific gravity is between 1.000-1.019, it indicates that the specific gravity is low; if the specific gravity is between 1.020-1.023, it indicates that the specific gravity is normal; if the specific gravity is between 1.024-1.030, it indicates that the specific gravity is high
• The external range of the scale indicates salinity (PPT), and the internal range of the scale indicates gravity. And clearly mark the safe area. Application range: 0-40 degrees (1.000-1.030). If the salinity PPT is between 32-40, it indicates that the salinity is high; if the salinity PPT is between 27-31, it indicates that the salinity is normal; if the salinity PPT is between 0-26, it indicates that the salinity hydrometer is low
• Wide range of applications: Suitable for salt water and sea water fish tanks. Perfect for testing salinity and specific gravity of saltwater and seawater tanks, including solubility and specific gravity scales. Suitable for fresh water and sea water
• Easy to read swing arm pointer and ultra wide stable base can provide accurate test results

ZRM&E

• Performance driven at affordable prices
• Made in the USA with quality materials
• Field tested to ensure nothing but the best for your pet
• Item Package Weight: 0.185

Fluval

• ✔ SPECIFICALLY DESIGNED REFRACTOMETER FOR SALTWATER AQUARIUM--The algorithm is made specifically for testing seawater and saltwater. This is different than a standard refractometer which is not calibrated to check salinity of aquarium water and will give an error in your readings.
• ✔ AUTOMATIC TEMPERATURE CALIBRATION --- The calibration process should be carried out with both the room and the instrument at 68° F. The refractive index of a liquid changes with temperature. Due to the automatic temperature calibration, any changes in ambient temperature from 50° F- 86° F will not affect the accuracy of the reading.
• ✔ EASY AND CLEAR READING FOR SALTWATER AQUARIUMS AND REEF TANKS--- The refractometer comes with a focus adjustment on the eyepiece, this will give you clarity of the optics and a sharp line for easy reading.
• ✔ COMES IN A SOLID CASE INCLUDES PIPETTE AND CALIBRATION TOOL --- This 7.6 inches refractometer is not only built extremely well, but it comes with a durable hard case for safe and easy storage of the refractometer when not in use. Includes everything you need: dropper, a screwdriver, a user manual, hard case and a cleaning cloth.
• ✔ KEEP YOUR FISH AND PLANT LIFE IN OPTIMAL HEALTH--- Clean, pure saltwater is crucial for the vitality of your marine or reef aquarium. Use this refractometer to measure the salinity of the water, the target level of salinity in a reef tank should be 35 ppt.

SunGrow

• Can remain submerged inside your aquarium or sump
• Know your salinity in a glance
• Compact design allows for discreet placement in the aquarium
• Ideal for all saltwater aquariums and sumps

Coralife