Editor's Choice - Our Favorite Sera Aquarium Hydrometers

1. 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']

Sera 8910 Final Thoughts

"I highly recommend!"

The refractor was off out off the box. Pretty darn accurate for the price. It's perfectly accurate based on the known calibration fluid. Now that it's calibrated I love it! 026 and the tank isn't, new animals will go into shock. Bought this one to check my old one, this one checked right on the dot at 1. All very easy and I feel as though I am getting an accurate salinity reading.

Overall Score
4.0

[star rating="4"]
(58 Points)

2. Pet Dog Cat Refractometer Pet Urine Specific Gravity Refractometer Serum Plasma Protein: 2~14g/dl, C...

User Ratings: 66 16

RZ First Impressions

"Clear directions."

Trying to turn it by hand won't work. The water was at what I expected it should be. I would recommend this product to anyone that has a marine aquarium. The instant ocean hydrometer will always be right. And it is much more accurate than my old salinity meter. This requires repeatedly tapping the arm with a pencil. Bubbles can greatly affect the reading.

  • Pet Dog Cat Refractometer Pet Urine Specific Gravity Refractometer Serum Plasma Protein: 2~14g/dl, Clinical Animal Refractometer Hydrometers Urine Tester 1.000-1.060SG for Veterinary Cat Dog Pets
  • TRIPLE SCALES REFRACTOMETER: Left scale for testing urine specific gravity of large animals such as dog, the middle scale can measure cats urine specific gravity or other small animals, the right scale tests serum or plasma protein level for all animals.
  • QUICK & EASY OPERATION: few sample than other lab hydrometers, just 2 or 3 drops of solution and wait for a few seconds, accurate data automatic shows, automatic temperature compensation 0°C-30°C/50°F to 86°F
  • MEASURING RANGE: Serum or plasma protein: 2-14g/dl, large animal like dog and small animals like cats’ urine specific gravity 1.000~1.060 SG, resolution: 0.001SG. Ideal for your home pets, clinical veterinary and pet owners.
  • DURABLE REFRACOMTER: comfortable holding and non-slip ABS rubberized grip, anti-rust aluminum body for long term using. Strictly quality and safety standards approved.
  • COMPACT SIZE: Lightweight and pocket size lab refractometer, comes with sturdy plastic box, mini screwdriver, pipette and wiping cloth and manual packed together, easy to carry and storage.
  • Manufacture: RZ
  • Editor's Impressions Of The RZ
  • Accuracy [star rating='4.5']
  • Quality [star rating='5']
  • Value For Money [star rating='4.7']
  • Affordability [star rating='3.9']

RZ Final Thoughts

"These seem spot on."

I have tried others before but this has given me accurate and stable results. Now that it's calibrated I love it! I use this to check the specific gravity of my marine aquarium. Looks to provide very accurate readings. Get precise salinity readings in moments. Make your own by simply boiling some water and collecting the condensate. I use this for my 10g brackish and it works ok.

Overall Score
4.0

[star rating="4"]
(8 Points)

3. Aquarium Refractometer, Seawater Salinity Meter Aquarium Optics Refractometer Temperature ATC Digita...

Hongzer First Impressions

"Easy to use."

Functions just as it is supposed to. It is essential to get some specialized aquarium calibration fluid for 1. It is easy to read and perform the procedure in seconds. It did not need adjusting to calibrate, though I tried to just to see how it worked. Once I figured that out, it works great. Be sure to buy the calibration solution and test this before use! So once your instant ocean shows a measurement.

  • Aquarium Refractometer, Seawater Salinity Meter Aquarium Optics Refractometer Temperature ATC Digital 0-10%
  • 0 to 10% salinity, 0.01% scale.
  • Durable aluminum body, durable and can use for a long time.
  • Adjust the focus by twisting the handle.
  • Compact design with rubber handle.
  • Soft and flexible eyepiece for added comfort. Instant and reliable aqueous solution measurement.
  • Manufacture: Hongzer
  • Item Weight: 8.4 ounces
  • Product Dimensions: 6.69 x 1.57 x 1.57 inches
  • Editor's Impressions Of The Hongzer
  • Accuracy [star rating='5']
  • Quality [star rating='5']
  • Value For Money [star rating='5']
  • Affordability [star rating='5']

Hongzer Final Thoughts

"So far so good."

It is a little cheaper made but it works great for the cost! Pretty darn accurate for the price. Ambient room light at night is not enough and makes what you're viewing dark. Normally that gives the more accurate reading. Now its easy to make sure I have the correct amount of salt in my aquariums. I was surprise that the product was really cheap compare to the other ones. This refractor should last a good number of years.

Overall Score
5.0

[star rating="5"]
(2 Points)

4. 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 [star rating='3.4']
  • Quality [star rating='3.3']
  • Value For Money [star rating='3']
  • Affordability [star rating='3.5']

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

[star rating="4"]
(69 Points)

5. LemonBest 0%-10% Automatic Temperature Compensation Salinity Refractometer Salt Water Aquariu...

User Ratings: 75 5

LemonBest First Impressions

"Great tool."

I don't want to deal with temperature correction or. When I compared it to what my local pet store was reading my water at it was dead on. Used distilled water to calibrate, the screw is located under the rubber cap. This one here was much cheaper,& exactly the same as they sold in the store. At first, I was getting bubbles sticking to the rotating arrow. Definitely a lot cheaper than a refractometer. I decided to upgrade and it was easy to calibrate.

  • LemonBest 0%-10% Automatic Temperature Compensation Salinity Refractometer Salt Water Aquarium by Lemonbest
  • Features with automatic temperature compensation (ATC) function
  • Designed for testing the concentration of salt water and brine, ideal for aquariums, marine monitoring and quality control in research and clinical laboratories
  • With just a couple of drops of aquarium water you know exactly what the salinity is
  • Measures on 2 scales, specific Gravity (D 20/20) and parts per thousand (‰), provides a direct reading of the specific gravity and concentration of salt in water
  • Comes with a hard case, dropper, screwdriver and cleaning cloth
  • Manufacture: Lemonbest
  • Product Dimensions: 7.87 x 1.57 x 1.57 inches; 3.88 Ounces
  • Editor's Impressions Of The LemonBest
  • Accuracy [star rating='5']
  • Quality [star rating='5']
  • Value For Money [star rating='5']
  • Affordability [star rating='5']

LemonBest Final Thoughts

"Easy to use."

Make sure to knock out the bubbles on the white dial by hitting it with your knuckle. It works OK but seems pretty flimsy and it's feel that way. My only criticism would be that it's a little too dark. I don't know if that's a positive or negative but just different. Just rinse with warm water afterwards. I bought this and a hydrometer because of the reviews saying its not accurate. Pretty darn accurate for the price.

Overall Score
4.5

[star rating="4.5"]
(315 Points)

6. Aquarium Salinity Refractometer for Brackish/Marine/Reef Tank Testing,Hobein Dual Scale Automatic Te...

User Ratings: 68 6

Hobein First Impressions

"Calibrate it, use it."

And always make sure there is no bubbles on the measuring unit. When I compared it to what my local pet store was reading my water at it was dead on. Be sure to adjust the focus by turning the eye focal when you first receive. Plus it is super easy to use and clean. Be sure to adjust the focus by turning the eye focal when you first receive. Was calibrated and worked perfect right out of the box. It is easy to read and perform the procedure in seconds.

  • Aquarium Salinity Refractometer for Brackish/Marine/Reef Tank Testing,Hobein Dual Scale Automatic Temperature Compensation 0-100ppt & 1.000-1.070 Specific Gravity with ATC
  • ❤DUAL SCALE: Measuring Ranges: 0-100 ppt of Salinity and 1.000 to 1.070 Specific Gravity (0-10%)the reading resolution is 0.1 %. Salinity Accuracy: +/-0.1%
  • ❤APPLICATIONS: Aquariums, Marine Monitoring, Agricultural, Gardening & Educational Purposes (Biology Projects)
  • ❤EASY TO USE:Automatic Temperature Compensation (ATC),Just need 2-3 drops of solution,you will be able to read accurately the result
  • ❤PORTABLE AND DURABLE: Made with non-staining, non-corrosive and non-reactive aluminum material, light-weighted and portable, safe and durable
  • ❤PACKAGE INCLUDES: 1 Refractometer, 1 Carrying Case, 1 Calibrating Screw Driver, 2 Pippets, 1 Cleaning Clothe, 1 Instruction Manual
  • Manufacture: Hobein
  • Editor's Impressions Of The Hobein
  • Accuracy [star rating='5']
  • Quality [star rating='4.9']
  • Value For Money [star rating='3.9']
  • Affordability [star rating='4.7']

Hobein Final Thoughts

"This tool does that."

Even the smallest bubble will throw the measurements way, way off. It came with all that was listed in the in production description. All very easy and I feel as though I am getting an accurate salinity reading. So once your instant ocean shows a measurement. But there are some ways to keep on getting accurate readings. Too that makes it appear too cheap. Excellent piece of equipment for the price.

Overall Score
4.4

[star rating="4.4"]
(290 Points)

7. 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']

Rhinoco RINTL277US Final Thoughts

"So far so good."

It is a little cheaper made but it works great for the cost! Simple to use, but if there are any air bubbles the results will be way off. But with alittle persistance I am able to read it. I would suggest purchasing the salt calibration solution. I got this to have a more accurate read than the hydrometer. And it is much more accurate than my old salinity meter. Waterproof if you accidentally drop it in the pool.

Overall Score
4.8

[star rating="4.8"]
(10 Points)

8. 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 [star rating='3.7']
  • Quality [star rating='4.2']
  • Value For Money [star rating='4.9']
  • Affordability [star rating='4.7']

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

[star rating="4.6"]
(43 Points)

9. 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 [star rating='4.8']
  • Quality [star rating='3.9']
  • Value For Money [star rating='5']
  • Affordability [star rating='4.5']

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

[star rating="4.7"]
(28 Points)

10. Pen Type Salinity & Temperature Meter ATC NaCl Salt Water Quality Tester for Saltwater Aquarium Hydr...

User Ratings: 49 17

Gain Express 837-2 First Impressions

"Easy to calibrate."

Just rinse with warm water afterwards. I run brackish tanks and it works perfectly. Hate the batteries, but once loaded, it seems to work fine. I tried it over and over and no bubbles! Excellent piece of equipment for the price. The water was at what I expected it should be. 026 and the tank isn't, new animals will go into shock.

  • Pen Type Salinity & Temperature Meter ATC NaCl Salt Water Quality Tester for Saltwater Aquarium Hydroponics Food
  • MEASURING RANGE: 0~9999 ppm or 10.0ppt~100.0ppt or 0.0%~10.0% or 0.950~1.080 (S.G.) based on NaCl with ±%F.S ±1 digit / ±0.5°C Accuracy
  • DISPLAY: Dual Temperature and Salinity in four measurement units (ppm, ppt, %, S.G) / 30 x 18mm LCD Size
  • APPLICATION: Salinity measurement in fish pond, tank, aquariums, laboratories, food processing, hydroponics, Aquaculture, and other water monitoring facilities.
  • FEATURES: Waterproof IP65 / One touch calibration / Auto power off and Non-Sleep mode disable / Multi points calibration
  • POWER SUPPLY / SENSOR : 4 x LR44 button batteries
  • User friendly easy to operate with One-touch calibration
  • Manufacture: Gain Express Holdings Ltd
  • Batteries: 4 LR44 batteries required.
  • Editor's Impressions Of The Gain Express 837-2
  • Accuracy [star rating='3.2']
  • Quality [star rating='4.1']
  • Value For Money [star rating='3.2']
  • Affordability [star rating='3.8']

Gain Express 837-2 Final Thoughts

"So, it does seem to work."

But with alittle persistance I am able to read it. Perfrct for someone learning or anyone for that matter. Once I adjusted the refractometer, my aquarium salinity read 1. Works great,& comes in a storage box. Works well on my Saltwater Aquarium. It did not need adjusting to calibrate, though I tried to just to see how it worked. Would be nice if stem were slightly larger for easier read.

Overall Score
3.8

[star rating="3.8"]
(99 Points)

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