Editor's Choice - Our Favorite KOOBOOK Aquarium Hydrometers

1. KOOBOOK 1 Pcs Accurate Hydrometer Salinity Meter 1.000-1.027 Salinity Range 0-36 for Aquarium Fish T...

User Ratings: 44 27

KOOBOOK First Impressions

"0, it reads 1."

Not sure how accurate it is, but it's a good reference point. I will get one later but for now this will do, since im just starting. It is heavy and easy to read in any light. Find a good light source to make reading easier. It works, we'll i assume it does as i have nothing to compare it to. If you read the directions in the box for the refractometer it's for freshwater. Good quality and simple to use refractometer.

  • KOOBOOK 1 Pcs Accurate Hydrometer Salinity Meter 1.000-1.027 Salinity Range 0-36 for Aquarium Fish Tank Marine Sea Saltwater
  • Made of high quality plastic, Withstand voltage,high transparency.
  • Special for culture of marine fish, the specific gravity and salinity of seawater are displayed once, easy to use and easy to read.
  • Keeping your hands clean,go underwater 15 cm (6 inch) depth to avoid errors caused by inhalation of oil film on the top of water.
  • When the water reaches full state (with the top of the baffle level), filed a hydrometer, this product can be hand or hang in the cylinder, automatic level function, can automatically find out the level to avoid the error.
  • Proper salinity level is one of the most important factors in the health of the fish.Readable and accuracy can up to ± 0.002 gravity unit.
  • Manufacture: KOOBOOK
  • Editor's Impressions Of The KOOBOOK
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

KOOBOOK Final Thoughts

"This tool does that."

It works, we'll i assume it does as i have nothing to compare it to. But with alittle persistance I am able to read it. I have purchased before will buy again! I have to recalibrate it ever use though which worries me sometimes. This requires repeatedly tapping the arm with a pencil. I would suggest purchasing the salt calibration solution. The reading is big enough for you to read and it comes with the batteries.

Overall Score
3.3


(11 Points)

2. 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
  • Quality
  • Value For Money
  • Affordability

V·RESOURCING COMINHKPR127692 Final Thoughts

"0, it reads 1."

However, the numbers are soooo small it is sometimes hard to read. I have to recalibrate it ever use though which worries me sometimes. When I saw the price offered on this one, I decided to buy and I love it. Not sure how accurate it is, but it's a good reference point. I would recommend this product to anyone that has a marine aquarium. Easy to use, easy to clean, easy to read. A hydrometer for making sure you have the right saltwater mix.

Overall Score
4.3


(31 Points)

3. capetsma Salinity Tester, Accurate Sea Hydrometer Aquarium Marine Salinity Meter for Fish Tank Pond ...

User Ratings: 56 11

capetsma First Impressions

"Great Product, Thanks!"

Be sure to adjust the focus by turning the eye focal when you first receive. There are conversion charts and tables online. I have gone two years in this hobby with a hydrometer. Get precise salinity readings in moments. It is a little cheaper made but it works great for the cost! Make your own by simply boiling some water and collecting the condensate. There are conversion charts and tables online.

  • capetsma Salinity Tester, Accurate Sea Hydrometer Aquarium Marine Salinity Meter for Fish Tank Pond Water Saltwater Freshwater Specific Gravity Test
  • 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.
  • Manufacture: Capetsma
  • Editor's Impressions Of The capetsma
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

capetsma Final Thoughts

"Easy to use."

Be sure to buy the calibration solution and test this before use! If you let it sit in the tank overnight, it definitely gives an accurate reading. Plenty of info on YouTube and the web if you don't know how. Works great,& comes in a storage box. Hate the batteries, but once loaded, it seems to work fine. Too that makes it appear too cheap. So worth it considering its great quality and great price.

Overall Score
4.0


(69 Points)

4. Coralife BioCube Mini Aquarium Hydrometer

User Ratings: 37 28

Coralife 100115642 First Impressions

"NO BUBBLES!"

My corals will be much happier now. Every time I leave to do something I come back and it's at the bottom of my tank. And it is much more accurate than my old salinity meter. This device is a godsend and so much easier and cleaner to use. It is a little cheaper made but it works great for the cost! Just give me one simple, accurate reading to go by, and I'm happy. When I saw the price offered on this one, I decided to buy and I love it.

  • Coralife BioCube Mini Aquarium Hydrometer
  • 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
  • Manufacture: Central Garden & Pet
  • Product Dimensions: 3.9 x 1 x 6 inches; 0.8 Ounces
  • Editor's Impressions Of The Coralife 100115642
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

Coralife 100115642 Final Thoughts

"I say it works very well."

Waterproof if you accidentally drop it in the pool. Do not spend money on calibration fluid to calibrate this meter. I use this for my 10g brackish and it works ok. I use this for my 10g brackish and it works ok. There are conversion charts and tables online. Wipe down glass surface to dry it and put it back on the shelf til next time. I would recommend you to purchase this and skip the other ones.

Overall Score
3.3


(57 Points)

5. UEETEK Heavy Duty Submersible Pump for Aquarium,Powerhead Fountain Water Hydroponic Pump with US-plu...

User Ratings: 51 49

UEETEK First Impressions

"Other then that."

Just give me one simple, accurate reading to go by, and I'm happy. Make sure to knock out the bubbles on the white dial by hitting it with your knuckle. Comes with a nice carrying case for easy and secure transportation. Does just as good of a job of any meter you would buy at the store! This is perfect to keep a check on the salt level in your tank. Small problem with bubbles on the needle but other than that no issues. Very easy, turn screw very slowly to calibrate.

  • UEETEK Heavy Duty Submersible Pump for Aquarium,Powerhead Fountain Water Hydroponic Pump with US-plug for Fish Tank,2.3 x 1.7 x 2.0 inch (L x W x H)
  • This submersible pump is designed for reliability and ultra-quiet operation.
  • Small size, high efficiency, low consumption, low noise.
  • Suction cups to fit vertical or horizontal mounting.
  • Suitable for use in hydroponic systems, ponds, fresh and saltwater aquariums, fountains and filter systems.
  • Note: The item is with US plug adapter:NLY for 110V, NOT for 220V. Please confirm the voltage of your area before placing an order.
  • Manufacture: UEETEK
  • Product Dimensions: 2.28 x 1.65 x 1.97 inches; 7.41 Ounces
  • Editor's Impressions Of The UEETEK
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

UEETEK Final Thoughts

"Nice product!"

So once your instant ocean shows a measurement. When I saw the price offered on this one, I decided to buy and I love it. There are conversion charts and tables online. Make sure to knock out the bubbles on the white dial by hitting it with your knuckle. Small problem with bubbles on the needle but other than that no issues. Like that it comes with everything needed. Don't spend your money on calibration solution.

Overall Score
3.1


(3 Points)

6. 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
  • Quality
  • Value For Money
  • Affordability

GXSTWU HY-2 Final Thoughts

"Seems pretty solid."

Hate the batteries, but once loaded, it seems to work fine. If you let it sit in the tank overnight, it definitely gives an accurate reading. Like that it comes with everything needed. Get precise salinity readings in moments. I have to recalibrate it ever use though which worries me sometimes. This one read perfect, and the others were completely inaccurate. Plus it is super easy to use and clean.

Overall Score
4.4


(265 Points)

7. Sinotech Hand Held Brix Honey Refractometer Rhb-90atc withCalibration Oil

Sinotech First Impressions

"This tool does that."

When I compared it to what my local pet store was reading my water at it was dead on. I would recommend this product to anyone that has a marine aquarium. Great product I used for beer making and my saltwater aquarium. Plus it is super easy to use and clean. I don't want to deal with temperature correction or. Get precise salinity readings in moments. Does just as good of a job of any meter you would buy at the store!

  • Sinotech Hand Held Brix Honey Refractometer Rhb-90atc withCalibration Oil
  • Test Fruit Brix And Honey Water
  • Heavy-duty and lightweight With its aluminum construction
  • ATC CompensationRange: 10°C~30°C (50°F~86°F)
  • Protable Type
  • 58-90%Brix 38-43 Be° (Baume) 12-27% Water
  • Manufacture: Sinotech
  • Editor's Impressions Of The Sinotech
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

Sinotech Final Thoughts

"NO BUBBLES!"

I bought this and a hydrometer because of the reviews saying its not accurate. I compared the readings using this hygrometer and the calibrated refractometer. Works great,& comes in a storage box. Used distilled water to calibrate, the screw is located under the rubber cap. So worth it considering its great quality and great price. My only criticism would be that it's a little too dark. This requires repeatedly tapping the arm with a pencil.

Overall Score
3.0


(1 Points)

8. KKmoon Salinity Refractometer, Handheld Seawater Hydrometers, Optical Salinity Tester, Portable ATC ...

User Ratings: 70 8

KKmoon First Impressions

"Decent case."

Hate the batteries, but once loaded, it seems to work fine. Get precise salinity readings in moments. I have a 2000+ gallon pond and I just put salt in it last month. The hydrometer is good, but I ordered two Shrimp CRS Miniature glass figurine, Clear. So once your instant ocean shows a measurement. All very easy and I feel as though I am getting an accurate salinity reading. The reading is big enough for you to read and it comes with the batteries.

  • KKmoon Salinity Refractometer, Handheld Seawater Hydrometers, Optical Salinity Tester, Portable ATC Refractometer, Dual Scale Saltwater Tester for Aquarium, Seawater, Pool, Fish Tank
  • Measure salt water or salinity of water, ideal for aquariums and marine monitoring.
  • With measurement level for direct reading. Adjustable manual focus, easy to focus and calibrate.
  • Handheld design and non-slip rubber handle for easy operation.
  • Instant Reading Result: Just need 2-3 drops of solution and a few seconds, you can get accurate readings.
  • Built-in automatic temperature compensation(ATC) to get faster results.
  • Manufacture: KKmoon
  • Item Weight: 8.9 ounces
  • Editor's Impressions Of The KKmoon
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

KKmoon Final Thoughts

"This tool is AMAZING!"

The refractor was off out off the box. I have a 2000+ gallon pond and I just put salt in it last month. Clear readout with the ability to calibrate and focus. I've tried several different refractometers now and they are mostly the same. He is too cute not to want to take care of properly. When I saw the price offered on this one, I decided to buy and I love it. Very easy, turn screw very slowly to calibrate.

Overall Score
4.2


(18 Points)

9. Premium Salinity Refractometer with Automatic Temperature Compensation for Saltwater, Aquarium, Mari...

User Ratings: 75 9

ONE250 First Impressions

"Arrived quickly."

I HIGHLY recommend this to Aquarists! Find a good light source to make reading easier. But with alittle persistance I am able to read it. My corals will be much happier now. I would recommend this product to anyone that has a marine aquarium. It's perfectly accurate based on the known calibration fluid. When I compared it to what my local pet store was reading my water at it was dead on.

  • Premium Salinity Refractometer with Automatic Temperature Compensation for Saltwater, Aquarium, Marine Reef Tank Testing - Dual Scale (0-100ppt & 1.000 to 1.070 S.G.)
  • ✔ Hand-held analog salt meter; Light-weight, portable, includes protective carrying case
  • ✔ Measures concentration of salt and dissolved solids in aqueous solution
  • ✔ Provides reading in parts per thousand (0-100PPT) and specific gravity (1.000 to 1.070 SG)
  • ✔ Ideal for on-site measurements in processing and storage areas, or in the field
  • ✔ Determine salinity during preparation of pickles, seafood products, frozen vegetables and fruits
  • Manufacture: ONE250
  • Product Dimensions: 8 x 3 x 2 inches; 9.14 Ounces
  • Editor's Impressions Of The ONE250
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

ONE250 Final Thoughts

"This tool does that."

Compare it with the refractometer and adjust the refractometer so that it matches. On the shaft of the refractometer, there's a little, rubber-covered nub. I bought this refractometer as a more accurate option for salinity than a hydrometer. Be sure to buy the calibration solution and test this before use! Bought this as a back up refractometer. 026 with the new Aquatic Experts fluid. I felt it wasn't accurate which was verified by my LFS.

Overall Score
4.5


(18 Points)

10. 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
  • Quality
  • Value For Money
  • Affordability

Gain Express REC-300ATC Final Thoughts

"These seem spot on."

Great tool if you have a salt-water fish tank or a decorative pond. My only criticism would be that it's a little too dark. I decided to upgrade and it was easy to calibrate. Definitely a lot cheaper than a refractometer. Even the smallest bubble will throw the measurements way, way off. Excellent piece of equipment for the price. Small problem with bubbles on the needle but other than that no issues.

Overall Score
5.0


(7 Points)

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