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. HunterBee Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automat...

User Ratings: 53

HunterBee First Impressions

"Would buy another!"

And it is much more accurate than my old salinity meter. It works, we'll i assume it does as i have nothing to compare it to. I have a 2000+ gallon pond and I just put salt in it last month. Find a good light source to make reading easier. On the shaft of the refractometer, there's a little, rubber-covered nub. It works, we'll i assume it does as i have nothing to compare it to. I would recommend this product to anyone that has a marine aquarium.

  • HunterBee Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automatic Temperature Compensation
  • 1.for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automatic Temperature Compensation
  • 2.Designed for direct reading of salt density in sea water.
  • 3.Rugged, durable construction - made from corrosion resistant brass.
  • 4.High contrast demarcation line for easy, accurate readings.
  • 5.Easily adjusted zero line by means of readily accessible screw.
  • Manufacture: 步仁科技
  • Editor's Impressions Of The HunterBee
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

HunterBee Final Thoughts

"Good product."

Simple to use, but if there are any air bubbles the results will be way off. I bought this and a hydrometer because of the reviews saying its not accurate. Be sure to buy the calibration solution and test this before use! I felt it wasn't accurate which was verified by my LFS. I've tried several different refractometers now and they are mostly the same. On the shaft of the refractometer, there's a little, rubber-covered nub. I tried it over and over and no bubbles!

Overall Score
4.2


(7 Points)

3. Ade Advanced Optics aaosal Professional Automatic Temperature Compensation Sea Water Salinity Refrac...

User Ratings: 68

Ade Advanced Optics aaosal First Impressions

"What else can I say."

I've tried several different refractometers now and they are mostly the same. When I saw the price offered on this one, I decided to buy and I love it. The refractor was off out off the box. I would suggest purchasing the salt calibration solution. I don't want to deal with temperature correction or. The product itself is very good quality and the included instructions are very clear. Looks to provide very accurate readings.

  • Ade Advanced Optics aaosal Professional Automatic Temperature Compensation Sea Water Salinity Refractometer for Aquarium, Hydrometer, 0-100 ppt and 1.000-1.070 Salinity S.G.
  • Manufacture: Ade Advanced Optics
  • Editor's Impressions Of The Ade Advanced Optics aaosal
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

Ade Advanced Optics aaosal Final Thoughts

"Arrived quickly."

This requires repeatedly tapping the arm with a pencil. 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. I have tried others before but this has given me accurate and stable results. I would suggest purchasing the salt calibration solution. It's fast, it's tidy, and it's accurate. When I compared it to what my local pet store was reading my water at it was dead on.

Overall Score
4.5


(9 Points)

4. Hikari AccuProbe Aquarium Hydrometer, Mini

User Ratings: 55 45

Hikari 96005 First Impressions

"NO BUBBLES!"

However, the numbers are soooo small it is sometimes hard to read. Make sure to knock out the bubbles on the white dial by hitting it with your knuckle. It's fast, it's tidy, and it's accurate. I did NOT calibrate, but am getting accurate readings. Definitely a lot cheaper than a refractometer. Ultimately, the measurement was exactly the same as our old tester. Calibrate with distilled water and test every so often.

  • Hikari AccuProbe Aquarium Hydrometer, Mini
  • Ideally suited for use in Nano tanks, smaller setups or sumps of larger systems
  • Accurate to 0.001 specific gravity and salinity (PPT) measurements
  • Durable construction for extended life
  • Designed to give a temperature-corrected reading in warm water aquariums – 68°F to 85°F (20°C to 30°C)
  • Readings can be taken by taking the meter out of the aquarium and placing on a level surface or leveling the unit in the substrate
  • Manufacture: Phillips Feed & Pet Supply Natural Balance
  • Product Dimensions: 5.2 x 1 x 3.5 inches; 0.8 Ounces
  • Editor's Impressions Of The Hikari 96005
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

Hikari 96005 Final Thoughts

"Just got it."

Next I calibrated the refractor with the calibration solution that I ordered too. Just give me one simple, accurate reading to go by, and I'm happy. Once I figured that out, it works great. So worth it considering its great quality and great price. Ultimately, the measurement was exactly the same as our old tester. Wipe down glass surface to dry it and put it back on the shelf til next time. It's a basic but reliable refractomer I use it for my aquariums.

Overall Score
3.2


(2 Points)

5. Pet Dog & Cat Refractometer,V-Resourcing Pet Urine Specific Gravity (1.000~1.060) Clinical Refractom...

User Ratings: 79

V·RESOURCING VLT065 First Impressions

"Seems pretty solid."

I found mine was calibrated out of the box. The water was at what I expected it should be. 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's a basic but reliable refractomer I use it for my aquariums. This refractometer came with two scales and Automatic Temperature Compensation. I got this to have a more accurate read than the hydrometer.

  • Pet Dog & Cat Refractometer,V-Resourcing Pet Urine Specific Gravity (1.000~1.060) Clinical Refractometer with Serum or Plasma Protein Test (2~14 g/100ml) for Veterinary Cat,Dog, Pets
  • 1.Hand-Held Pet Urine Specific Gravity Refractometer with Automatic Temperature Compensation(ATC: 10℃~30℃)
  • 2.[ Measuring Range ] Dog Urine Specific Gravity:1.000~1.060 ; Cat Urine Specific Gravity:1.000~1.060 ; Serum or Plasma Protein:2~14 g/100ml
  • 3.[ Easy to use ] Place 2 - 3 drops of sample onto the prism, and then look through the eyepiece for both Brix and Specific Gravity readings
  • 4.[ Convenient to store ] Compact in size and light in weight, packed with a plastic case, convenient to store and carry around
  • 5.[ Application ] This product provides quick and accurate indication of vital fluids levels.Ideal for clinical usage and intended for Veterinary
  • N.W. of a piece: about 102g
  • Product Size:19.5*4*4cm
  • Package Weight:237g
  • Manufacture: V-Resourcing
  • Editor's Impressions Of The V·RESOURCING VLT065
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

V·RESOURCING VLT065 Final Thoughts

"Massive peace of mind."

I HIGHLY recommend this to Aquarists! I will update later to see if the refractor will keep its calibration. When I saw the price offered on this one, I decided to buy and I love it. Pretty darn accurate for the price. Too that makes it appear too cheap. Small problem with bubbles on the needle but other than that no issues. Bubbles can greatly affect the reading.

Overall Score
4.7


(28 Points)

6. Amzdeal Salinity Refractometer Aquarium & Seawater - Dual Scale (1.0 to 1.070 S.G.)

User Ratings: 66 12

amzdeal First Impressions

"Seems to work fine."

Hate the batteries, but once loaded, it seems to work fine. For the price you definitley cant beat this meter is great! I would recommend this product to anyone that has a marine aquarium. Make sure to knock out the bubbles on the white dial by hitting it with your knuckle. I was surprise that the product was really cheap compare to the other ones. I don't want to deal with temperature correction or. This is perfect to keep a check on the salt level in your tank.

  • Amzdeal Salinity Refractometer Aquarium & Seawater - Dual Scale (1.0 to 1.070 S.G.)
  • 【Automatic Temperature Compensation】 Hand-held ATC refractometer, can be used in the temperature 5-30 ℃ / 41-86℉
  • 【Dual Salinity Scale】Salt content 0 ~ 100 ‰ (0 ~ 10%) and Salt specific gravity 1.000 ~ 1.070sg. Minimum scale is 1 ‰ (0.1%) or 0.001sg, more precise
  • 【Easy to Use】Using distilled water to calibrate and then you can measure the saltwater and get the result
  • 【Package Content】Come with all the accessories, including Dropper, Screwdriver, Cleaning Cloth, Storage Case and User Manual
  • 【Widely Use】This refractometer can be used to measure the salt content or sugar content, good for aquariums and marine monitoring
  • Manufacture: Amzdeal
  • Editor's Impressions Of The amzdeal
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

amzdeal Final Thoughts

"Massive peace of mind."

Be sure to adjust the focus by turning the eye focal when you first receive. Even the smallest bubble will throw the measurements way, way off. YOU WILL NOT get an accurate reading if there are bubbles on the needle. I use this to check the specific gravity of my marine aquarium. When I saw the price offered on this one, I decided to buy and I love it. Excellent piece of equipment for the price. Perfrct for someone learning or anyone for that matter.

Overall Score
4.2


(56 Points)

7. Aeroway Salinity Refractometer, Aquarium & Seawater - Dual Scale (1.0 to 1.070 S.G.)

User Ratings: 79 3

Aeroway 8541957182 First Impressions

"021 the other read."

Make sure to knock out the bubbles on the white dial by hitting it with your knuckle. Normally that gives the more accurate reading. I will get one later but for now this will do, since im just starting. I run brackish tanks and it works perfectly. I strongly recommend a refractometer vs. This device is a godsend and so much easier and cleaner to use. On the shaft of the refractometer, there's a little, rubber-covered nub.

  • Aeroway Salinity Refractometer, Aquarium & Seawater - Dual Scale (1.0 to 1.070 S.G.)
  • Measure salt water or salinity of water, ideal for aquariums and marine monitoring.
  • Features automatic temperature compensation (ATC),The main part is made of chromium, it's very durable.
  • Measures on 2 scales, Specific Gravity (D 20/20) and parts per thousand (‰).
  • Comes with hard case, dropper, screwdriver and cleaning cloth.
  • We offer premium quality and the best service, no matter what reason cause dissatisfaction,just return it within 30 days for a full refund. No questions asked, no hassle.
  • Manufacture: Aeroway
  • Editor's Impressions Of The Aeroway 8541957182
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

Aeroway 8541957182 Final Thoughts

"Works great!"

Simple to use, but if there are any air bubbles the results will be way off. I compared the readings using this hygrometer and the calibrated refractometer. Normally that gives the more accurate reading. It's a basic but reliable refractomer I use it for my aquariums. Every time I leave to do something I come back and it's at the bottom of my tank. I bought this and a hydrometer because of the reviews saying its not accurate. So worth it considering its great quality and great price.

Overall Score
4.6


(43 Points)

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
  • 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)

9. RZ Aquariums Salinity Refractometer for Seawater Marine Fish-Keeping, Dual Scales Specific Gravity S...

User Ratings: 74 3

RZ First Impressions

"Great product."

I bought this salinity meter for my aquarium. I needed this product and it is a lot less expensive than the local aquarium store. When I saw the price offered on this one, I decided to buy and I love it. Works well on my Saltwater Aquarium. I was surprise that the product was really cheap compare to the other ones. But there are some ways to keep on getting accurate readings. Too that makes it appear too cheap.

  • RZ Aquariums Salinity Refractometer for Seawater Marine Fish-Keeping, Dual Scales Specific Gravity Salinity Meter Hydrometer 0-100ppt & 1.000-1.070, Saltwater Tester with ATC Function
  • Measures on 2 Scales: Aquariums refractometer features Specific Gravity (D 20/20) 1.000-1.070sg and parts per thousand 0-100PPT (1‰=1ppt=1000ppm)
  • Seawater refractometer measures saltwater or salinity of water, ideal for aquarium, marine monitoring, fish-keeping,salty pools&spas and etc.
  • ATC Function: salty water refractometer with automatic temperature compensation, allow you obtain accurate readings easier and faster
  • Salinity Refractometer is made of aluminum body and ABS rubber light and very sturdy, comes with a hard plastic case, a mini screwdriver, a dropper
  • Easy to Use: put 2-3 drops on the saltwater’s prism, towards light then to get the accurate readings through the optic eyepiece, ideal for replacement the poor quality and difficult to read hydrometer refractometer
  • Manufacture: RZ
  • Editor's Impressions Of The RZ
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

RZ Final Thoughts

"Seems to work fine."

I will get one later but for now this will do, since im just starting. Comes with a nice carrying case for easy and secure transportation. I decided to upgrade and it was easy to calibrate. Plenty of info on YouTube and the web if you don't know how. Small problem with bubbles on the needle but other than that no issues. The reading is big enough for you to read and it comes with the batteries. Be sure to adjust the focus by turning the eye focal when you first receive.

Overall Score
4.6


(296 Points)

10. 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)

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