Editor's Choice - Our Favorite Kocome Aquarium Hydrometers

1. Kocome Marine Hydrometer Reef Fish Tank Aquarium Water Salinity Specific Gravity Tester

User Ratings: 71

Kocome First Impressions

"Great kit."

I use this for my 10g brackish and it works ok. Plus it is super easy to use and clean. I did NOT calibrate, but am getting accurate readings. I needed this product and it is a lot less expensive than the local aquarium store. It's fast, it's tidy, and it's accurate. But with alittle persistance I am able to read it. Don't care much for having to post a review in order to activate warranty.

• Kocome Marine Hydrometer Reef Fish Tank Aquarium Water Salinity Specific Gravity Tester
• Accurate and easy to read.
• Size: 3.54×4.72×0.59in (Approx.).
• Readings are temperature-corrected & accurate to +/- 0. 002 specific gravity units which range from 1. 000 - 1. 030 specific gravity.
• It is optimum to be put into below 6" deep water, so it can avoid the error from the oil slick.
• Perfect for testing both salinity and specific gravity of your brackish and marine tank.
• Manufacture: KOCOME

• Editor's Impressions Of The Kocome
• Accuracy [star rating='3.6']
• Quality [star rating='4.2']
• Value For Money [star rating='4']
• Affordability [star rating='3.9']

Here Are Some Other Related Aquarium Hydrometers

2. Abuycs Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium, Saltwater Tester Hydrome...

User Ratings: 86

Abuycs First Impressions

"This tool is AMAZING!"

I have gone two years in this hobby with a hydrometer. I will get one later but for now this will do, since im just starting. The unit is really easy to calibrate and used. I use this for my 10g brackish and it works ok. My meter came already calibrated to 0. The instant ocean hydrometer will always be right. Works well on my Saltwater Aquarium.

• Abuycs Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium, Saltwater Tester Hydrometer, Dual Sacle 0-100ppt & 1.000-1.070 Specific Gravity with ATC Automatic Temperature Compensation
• ✅DUAL SCALE MEASURES SALT PERCENT AND SG:Specific gravity,range: 1.000-1.070 g/cm3, resolution: 0.001 g/cm3.Salt percent, range: 0-100 ppt ( or say parts per thousand), resolution: 1 ppt.It is designed for the measurement of seawater (marine aquaria) or very low concentrated salt solutions.
• ✅ ENDLESS APPLICATION AND EASY TO USE,:Ideal for testing and monitoring aquariums,fish tank, saltwater pool,seawater.Just need 2-3 drops of solution, you can get accurate readings. No batteries needed.
• ✅ATC TECHNOLOGY:Handheld Salinity Refractometerr with Automatic Temperature Compensation(ATC),no more worry about the temperature change will influence the reading accuracy.the fish keeping refractometer will account for changes in ambient temperature and automatically compensate accordingly to provides accurate and repeatable measurements.
• ✅AIRCRAFT ALUMIUM BODY MATERIAL:The aquarium refractometer is made of non-staining, non-corrosive and non-reactive aluminum which is lightweight to carry,anti-scratch and durable.
• ✅WIDE APPLICATION: It is for measuring the salinity of salt water quickly and accurately, ideal for agriculture, industry and research application, such as mariculture, fish culture, aquarium, marine survey, water quality monitoring, salt production, manufacture of normal saline, salinity measurement in food processing etc. Can also be used for medical institutions, university research and so on.
• Manufacture: Rockgood ltd.

• Editor's Impressions Of The Abuycs
• Accuracy [star rating='4']
• Quality [star rating='5']
• Value For Money [star rating='5']
• Affordability [star rating='5']

3. Clinical Refractometer with ATC, Tri-Scale Serum Plasma Protein Test 2-14g/dl Urine Specific Gravity...

Gain Express REC-300ATC First Impressions

"Matches my hydrometer."

YOU WILL NOT get an accurate reading if there are bubbles on the needle. If you let it sit in the tank overnight, it definitely gives an accurate reading. Even the smallest bubble will throw the measurements way, way off. It is easy to read and perform the procedure in seconds. Pretty darn accurate for the price. Easy to use, easy to clean, easy to read. Definitely a lot cheaper than a refractometer.

• Clinical Refractometer with ATC, Tri-Scale Serum Plasma Protein Test 2-14g/dl Urine Specific Gravity 1.000-1.060SG, for Veterinary Vet Cat Dog Pets
• Animal clinical refractometer Tri Scale for Dog Cat Test of Serum protein and Urine specific gravity
• TRIPLE SCALE: Dog Scale Urine Specific Gravity is for Large Animal, Cat Scale Urine Specific Gravity is for Small Animal and Serum or Plasma Protein Scale for all animals
• MEASURING RANGE: Dog and Cat Urine specific gravity: 1.000 - 1.060SG ; Serum Protein: 2-14g/dl
• Cushioned w/ soft and comfortable non-slip rubberized grip, insulate test solution from body heat
• Auto Temperature Compensation (ATC), rest easy that your measurements are always accurate regardless of temperature variation
• Manufacture: Gain Express Holdings Ltd
• Part Number: REC-300ATC
• Item Weight: 9.2 ounces
• Color: Urine Sg / Serum Protein
• Batteries Included?: No
• Batteries Required?: No

• Editor's Impressions Of The Gain Express REC-300ATC
• Accuracy [star rating='4.2']
• Quality [star rating='5']
• Value For Money [star rating='5']
• Affordability [star rating='4.2']

4. AUTOUTLET Refractometer Saltwater Aquarium for Seawater,Pool,Tank,Testing,Marine Fishkeeping, 0-100P...

User Ratings: 83 2

AUTOUTLET 8541957195 First Impressions

"These seem spot on."

Not sure how accurate it is, but it's a good reference point. Ambient room light at night is not enough and makes what you're viewing dark. If you read the directions in the box for the refractometer it's for freshwater. And it is much more accurate than my old salinity meter. Waterproof if you accidentally drop it in the pool. My corals will be much happier now. It is a little cheaper made but it works great for the cost!

• AUTOUTLET Refractometer Saltwater Aquarium for Seawater,Pool,Tank,Testing,Marine Fishkeeping, 0-100PPT & 1.000-1.070 Salinity Tester with ATC Function Hydrometer Specific Gravity Salinity Meter Kit
• 【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.
• Due to the difference of human focal lengths,when during adjusting, you may just need to rotate in reverse or re-adjust the distance between your eye and the eyepiece.
• It's necessary to keep the surrounding environment with sufficient brightness and suitable temperature during use. Generally,there is no error in the temperature between 10℃-30℃.(50℉-86℉)
• Specific Gravity (D 20/20) and parts per thousand and replaces your poor quality and difficult to read hydrometer.
• Manufacture: AUTOUTLET
• Product Dimensions: 7.87 x 3.54 x 2.36 inches; 8.48 Ounces

• Editor's Impressions Of The AUTOUTLET 8541957195
• Accuracy [star rating='5']
• Quality [star rating='4.2']
• Value For Money [star rating='4.9']
• Affordability [star rating='5']

5. Pen Type Salinity & Temp Meter Measurement Units Checker Quality Tester ATC for Pond Pool Saltwater ...

User Ratings: 36 25

TEKCOPLUS SMTK-49_SOL First Impressions

"So here's the verdict."

Just give me one simple, accurate reading to go by, and I'm happy. This is perfect to keep a check on the salt level in your tank. He is too cute not to want to take care of properly. Bought this as a back up refractometer. Get precise salinity readings in moments. The unit is really easy to calibrate and used. My only criticism would be that it's a little too dark.

• Pen Type Salinity & Temp Meter Measurement Units Checker Quality Tester ATC for Pond Pool Saltwater Aquarium Cooking Seawater Drinking Water (Salinity Meter 70.0ppt + Buffer Sol'n)
• Ideal for checking salt in fish tanks and aquariums, water monitoring, seawater-prepared food solutions, holding tanks and more!
• Measuring Range: Salinity: 0.00~10.0 ppt (NaCL) and 10.1~70.0ppt (NaCL)
• Auto Power-Off Function with disable feature
• °C/°F unit switchable ,Easy one-touch calibration, Waterproof Rating: IP65
• Calibration set: Buffer NaCI 50ppt and calibration guideline
• Manufacture: TekcoPlus Ltd

• Editor's Impressions Of The TEKCOPLUS SMTK-49_SOL
• Accuracy [star rating='3.8']
• Quality [star rating='3.8']
• Value For Money [star rating='2.6']
• Affordability [star rating='3']

6. Rhinoco Salinity Refractometer, Saltwater Aquarium Refractometer, Dual Scales Specific Gravity Salin...

User Ratings: 75

Rhinoco RINTL277US First Impressions

"Great product!"

I bought this salinity meter for my aquarium. I will get one later but for now this will do, since im just starting. Get precise salinity readings in moments. Great, I be had this b4 ez to test salt level. Even the smallest bubble will throw the measurements way, way off. However, the numbers are soooo small it is sometimes hard to read. I compared the readings using this hygrometer and the calibrated refractometer.

• Rhinoco Salinity Refractometer, Saltwater Aquarium Refractometer, Dual Scales Specific Gravity Salinity Meter with 0-100 PPT and 1.000-1.070 for Seawater, Pool, Tank, Testing, Marine Fishkeeping
• 【Salinity Refractometer】Measure Salt Water or Salinity of Water, ideal for Aquariums, Marine Monitoring, Agricultural, Gardening & Educational Purposes.
• 【Automatic Temperature Compensation】Salinity Tester Built-in ATC, which Accounts for Changes in Ambient Temperature and Automatically Compensates Accordingly to Guarantee Consistently Accurate Readings.
• 【Dual Salinity Scale】Salinity Mester with Dual Scale 0-100 ppt(0 - 10 %) of Salinity and 1.000 to 1.070 Specific Gravity (0-10%).
• 【Full Copper Chrome Plated Design】Sturdy & Compact, the Eyepiece is in High Quality for Better Viewing, Adopting Optical Glass Lens Rather than Plastic Lens for Accurate Measurement.
• 【Accessories & Warranty】1 x Salinity Refractometer, 1 x Plastic Pipette, 1 x Mini Screw Driver, 1 x Cleaning Cloth and User Manual, Comes with 18-Month Warranty!
• Manufacture: Rhinoco

• Editor's Impressions Of The Rhinoco RINTL277US
• Accuracy [star rating='3.8']
• Quality [star rating='5']
• Value For Money [star rating='3.9']
• Affordability [star rating='4.5']

7. GXSTWU Reptile Hygrometer Thermometer LCD Display Digital Reptile Tank Hygrometer Thermometer with H...

User Ratings: 71 5

GXSTWU HY-2 First Impressions

"Couldn't be happier."

I compared the readings using this hygrometer and the calibrated refractometer. But with alittle persistance I am able to read it. Not sure how accurate it is, but it's a good reference point. There are conversion charts and tables online. I will get one later but for now this will do, since im just starting. So once your instant ocean shows a measurement. Find a good light source to make reading easier.

• GXSTWU Reptile Hygrometer Thermometer LCD Display Digital Reptile Tank Hygrometer Thermometer with Hook Temperature Humidity Meter Gauge for Reptile Tanks, Terrariums, Vivarium
• 100% Brand New and High-Quality Reptile Tank Thermometer Hygrometer: Precise supervision of the temperature and air humidity in terrariums, vivariums and reptile tanks.
• Stylish Design: Stylish looking digital vivarum thermometer with hook and loop for easy to install to any reptile tanks or terrariums. Comes with a battery so you can use the thermometer immediately.
• Fantastic Value: This accurate reptile thermometer and hygrometer allows you to monitor the temperature and humidity in the reptile tanks at all times to makesure your beloved reptiles are in perfect health.
• Fahrenheit Celsius Convertible: Temperature can be display in Fahrenheit or Celsius by press the C/F hole on the back of the item with a paper clip.
• Quality Guaranteed: Our carefully sourced range of thermometer hygrometers are manufactured to the highest of standards our customers expect. And provide 365 days warranty, in case of any quality problems, please feel free to contact us by email, we will give you a satisfactory solution.
• Manufacture: Cangda Electronics Co., Ltd.
• Product Dimensions: 2.09 x 0.67 x 1.3 inches; 0.92 Ounces
• Batteries: 1 LR44 batteries required. (included)

• Editor's Impressions Of The GXSTWU HY-2
• Accuracy [star rating='4.7']
• Quality [star rating='4.7']
• Value For Money [star rating='3.5']
• Affordability [star rating='4.8']

8. Seawater Salinity Refractometer,V-Resourcing Automatic Temperature Compensation Sea Water Salinity M...

User Ratings: 64 8

V·RESOURCING COMINHKPR127692 First Impressions

"Good product."

I have tried others before but this has given me accurate and stable results. All very easy and I feel as though I am getting an accurate salinity reading. I did NOT calibrate, but am getting accurate readings. YOU WILL NOT get an accurate reading if there are bubbles on the needle. I run brackish tanks and it works perfectly. 027, I'm so glad I bought this one and it came spot on. Definitely a lot cheaper than a refractometer.

• Seawater Salinity Refractometer,V-Resourcing Automatic Temperature Compensation Sea Water Salinity Measurer for Aquarium, Hydrometer, 0-100ppt & 1.000-1.070 Salinity Specific Gravity
• Automatic Temperature Compensation: 10℃~30℃
• Measuring range: salinity: 0-100 ‰, Specific Gravity : 1.000 to 1.070
• Minimum scale: salinity: 1 ‰, Specific Gravity : 0.001
• Resolution: salinity: ±1‰, Specific Gravity : 0.001 mm
• Perfect for salty water tank and aquarium, seafood water tank, salty pools & spas and etc
• 1*Salinity Refractometer
• 1*Mini-screwdriver
• 1*Pipette
• Manufacture: V-Resourcing
• Product Dimensions: 8 x 3 x 2 inches; 8 Ounces

• Editor's Impressions Of The V·RESOURCING COMINHKPR127692
• Accuracy [star rating='4.1']
• Quality [star rating='3.3']
• Value For Money [star rating='5']
• Affordability [star rating='5']

9. Bubble Magus Digital Color Screen Salinity Meter

Bubble Magus First Impressions

"Good value."

YOU WILL NOT get an accurate reading if there are bubbles on the needle. Every time I leave to do something I come back and it's at the bottom of my tank. On the shaft of the refractometer, there's a little, rubber-covered nub. However, the numbers are soooo small it is sometimes hard to read. Just rinse with warm water afterwards. I use this for my 10g brackish and it works ok. Bought this as a back up refractometer.

• Bubble Magus Digital Color Screen Salinity Meter
• Manufacture: Bubble Magus

• Editor's Impressions Of The Bubble Magus
• Accuracy [star rating='4.8']
• Quality [star rating='5']
• Value For Money [star rating='4.1']
• Affordability [star rating='4.7']

10. Sera Marin Hydrometer

User Ratings: 51 7

Sera 8910 First Impressions

"Easy to calibrate."

He is too cute not to want to take care of properly. My only criticism would be that it's a little too dark. I have to recalibrate it ever use though which worries me sometimes. Too that makes it appear too cheap. I have tried others before but this has given me accurate and stable results. The water was at what I expected it should be. This requires repeatedly tapping the arm with a pencil.

• Sera Marin Hydrometer
• Country Of Origin : China
• The Package Height Of The Product Is 7.48 Inches
• The Package Length Of The Product Is 2 Inches
• The Package Width Of The Product Is 1.38 Inches
• Manufacture: Sera North America, Inc.
• Product Dimensions: 1.18 x 1.38 x 7.48 inches; 1.28 Ounces

• Editor's Impressions Of The Sera 8910
• Accuracy [star rating='5']
• Quality [star rating='4.6']
• Value For Money [star rating='4.1']
• Affordability [star rating='3.8']