Editor's Choice - Our Favorite Fluval Aquarium Hydrometers

1. Fluval Sea Hydrometer for Aquarium, Medium

User Ratings: 46 17

Fluval 14356 First Impressions

"Works perfectly."

Hate the batteries, but once loaded, it seems to work fine. Like that it comes with everything needed. There are conversion charts and tables online. Now its easy to make sure I have the correct amount of salt in my aquariums. The product itself is very good quality and the included instructions are very clear. The reading is big enough for you to read and it comes with the batteries. Small problem with bubbles on the needle but other than that no issues.

  • Fluval Sea Hydrometer for Aquarium, Medium
  • Helps measure specific gravity and salt level in marine aquariums
  • Features large, easy to read markings
  • Simple design-blends in easily
  • Item Package Weight: 0.185
  • Manufacture: Fluval
  • Item Weight: 0.81 ounces
  • Product Dimensions: 1 x 5.5 x 7.9 inches
  • Editor's Impressions Of The Fluval 14356
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

Fluval 14356 Final Thoughts

"Works great for reefing!"

Great tool if you have a salt-water fish tank or a decorative pond. I strongly recommend a refractometer vs. It works, we'll i assume it does as i have nothing to compare it to. Definitely a lot cheaper than a refractometer. Great product I used for beer making and my saltwater aquarium. It came with all that was listed in the in production description. Plenty of info on YouTube and the web if you don't know how.

Overall Score
3.7


(373 Points)

2. 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
  • Quality
  • Value For Money
  • Affordability

AUTOUTLET 8541957195 Final Thoughts

"2 failed, 3 did not."

Just rinse with warm water afterwards. I bought this and a hydrometer because of the reviews saying its not accurate. Now that it's calibrated I love it! I HIGHLY recommend this to Aquarists! I have purchased before will buy again! I got this to have a more accurate read than the hydrometer. Too that makes it appear too cheap.

Overall Score
4.7


(757 Points)

3. 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)

4. 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)

5. Instant Ocean SeaTest Hydrometer

User Ratings: 59 6

Instant Ocean TK-504 First Impressions

"Calibrate it, use it."

Make your own by simply boiling some water and collecting the condensate. This one here was much cheaper,& exactly the same as they sold in the store. My only criticism would be that it's a little too dark. Normally that gives the more accurate reading. Used distilled water to calibrate, the screw is located under the rubber cap. Once I adjusted the refractometer, my aquarium salinity read 1. Hate the batteries, but once loaded, it seems to work fine.

  • Instant Ocean SeaTest Hydrometer
  • Marine hydrometer: Tests salinity and specific gravity in marine aquariums to help maintain a healthy tank
  • Accurate: Precise, full-range readings - accurate to +/- 0
  • Ready to use: Simply dunk in aquarium to fill with water, then set on level surface to read
  • Easy to read: Clearly marked to show results
  • Extra-wide stabilizer base: Two-color scale with a safe zone for simple results
  • Manufacture: Instant Ocean
  • Item Weight: 0.8 ounces
  • Product Dimensions: 6.3 x 4.2 x 1.3 inches
  • Editor's Impressions Of The Instant Ocean TK-504
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

Instant Ocean TK-504 Final Thoughts

"Good price."

Simple to use, but if there are any air bubbles the results will be way off. The instant ocean hydrometer will always be right. 026 with the new Aquatic Experts fluid. Now its easy to make sure I have the correct amount of salt in my aquariums. Looks to provide very accurate readings. Easy to use, easy to clean, easy to read. My only criticism would be that it's a little too dark.

Overall Score
4.2


(426 Points)

6. Dual Scale Salinity Refractometer ATC 0-100ppt (0-10%) & 1.000-1.070 Specific Gravity, Portable Mete...

User Ratings: 76 4

Gain Express RES-10ATC First Impressions

"Documentation is limited."

So once your instant ocean shows a measurement. And always make sure there is no bubbles on the measuring unit. Make sure to knock out the bubbles on the white dial by hitting it with your knuckle. But with alittle persistance I am able to read it. Make your own by simply boiling some water and collecting the condensate. Works great,& comes in a storage box. Trying to turn it by hand won't work.

  • Dual Scale Salinity Refractometer ATC 0-100ppt (0-10%) & 1.000-1.070 Specific Gravity, Portable Meter Tester for Seawater Salt Sea Water Aquarium Brackish Reef Tank Marine
  • Range: 0-100ppt (0-10% Salinity) and Density/ Specific Gravity 1.000-1.070 1ppt Salinity and 0.001 g/cm3 Density Resolutions
  • Water or a salt (brine) refractometer preferred by aquarist, it checks saltwater & brine or salinity of water, best for aquariums and marine monitoring
  • True seawater or a salt (brine) refractometer preferred by aquarist
  • Calibrate simply by distilled water, comes with free screwdriver for calibration
  • Has automatic temperature compensation (ATC) and has built with the highest and finest quality of aluminum & rubbe
  • Manufacture: Gain Express Holdings Ltd
  • Part Number: REB-32ATC
  • Material: ABS Material for Handle
  • Item Weight: 9.9 ounces
  • Color: 0-10% Salinity
  • Batteries Included?: No
  • Batteries Required?: No
  • Editor's Impressions Of The Gain Express RES-10ATC
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

Gain Express RES-10ATC Final Thoughts

"Good product."

For the price you definitley cant beat this meter is great! Now its easy to make sure I have the correct amount of salt in my aquariums. Comes with a nice carrying case for easy and secure transportation. Get precise salinity readings in moments. I have tried others before but this has given me accurate and stable results. Im using it for trying to create water conditions for amano zoes. I couldn't decide between this and one of the float arm meters or both.

Overall Score
4.6


(49 Points)

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
  • 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)

8. 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
  • Quality
  • Value For Money
  • Affordability

Bubble Magus Final Thoughts

"Easy to use."

Functions just as it is supposed to. Be sure to buy the calibration solution and test this before use! Ambient room light at night is not enough and makes what you're viewing dark. It is a little cheaper made but it works great for the cost! I decided to upgrade and it was easy to calibrate. I would recommend this product to anyone that has a marine aquarium. So worth it considering its great quality and great price.

Overall Score
5.0


(1 Points)

9. 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
  • Quality
  • Value For Money
  • Affordability

Abuycs Final Thoughts

"Easy instructions."

The refractor was off out off the box. However, the numbers are soooo small it is sometimes hard to read. I needed this product and it is a lot less expensive than the local aquarium store. Don't spend your money on calibration solution. However, the numbers are soooo small it is sometimes hard to read. Works well on my Saltwater Aquarium. 027, I'm so glad I bought this one and it came spot on.

Overall Score
4.6


(10 Points)

10. NEW RHS-10ATC 0-10% Salinity Refractometer Salt Water Aquarium

User Ratings: 53 7

Ade Advanced Optics RHS-10ATC First Impressions

"So, it does seem to work."

Definitely a lot cheaper than a refractometer. I bought this refractometer as a more accurate option for salinity than a hydrometer. But there are some ways to keep on getting accurate readings. I bought this salinity meter for my aquarium. 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. I don't know if that's a positive or negative but just different.

  • NEW RHS-10ATC 0-10% Salinity Refractometer Salt Water Aquarium
  • Manufacture: Ade Advanced Optics®
  • Editor's Impressions Of The Ade Advanced Optics RHS-10ATC
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

Ade Advanced Optics RHS-10ATC Final Thoughts

"I recommended!"

I bought this and a hydrometer because of the reviews saying its not accurate. I have gone two years in this hobby with a hydrometer. Very easy, turn screw very slowly to calibrate. Very quick to calibrate and to use. Just give me one simple, accurate reading to go by, and I'm happy. Clear readout with the ability to calibrate and focus. Excellent piece of equipment for the price.

Overall Score
3.9


(68 Points)

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