Editor's Choice - Our Favorite Gain Express Aquarium Hydrometers

1. 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
  • Quality
  • Value For Money
  • Affordability

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


(99 Points)

Peoples Choice - Other Highly Rated Gain Express Aquarium Hydrometers

2. 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)

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
  • 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)

4. HydroLogic HLTDS DM-2 Industrial Monitor

HydroLogic HLTDS First Impressions

"Case is nice as well."

Don't care much for having to post a review in order to activate warranty. YOU WILL NOT get an accurate reading if there are bubbles on the needle. The water was at what I expected it should be. However, the numbers are soooo small it is sometimes hard to read. Get precise salinity readings in moments. Was calibrated and worked perfect right out of the box. I would suggest purchasing the salt calibration solution.

  • HydroLogic HLTDS DM-2 Industrial Monitor
  • Measures The Flow Of Untreated Water Coming In Versus Purified Water Going Out
  • Comes Equipped With A 1/2" Inlet And 3/8Th Inch Outlet
  • Features An Auto-Off Function To Conserve Battery Power
  • No Assembly Required
  • Manufacture: Hydro-Logic
  • Item Weight: 2.38 pounds
  • Product Dimensions: 7.2 x 5.1 x 1.7 inches
  • Editor's Impressions Of The HydroLogic HLTDS
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

HydroLogic HLTDS Final Thoughts

"Using for my Pacman frog."

Looks to provide very accurate readings. It is a little cheaper made but it works great for the cost! I've checked about 5 times with the hydrometer and each time has been near perfect. Once I figured that out, it works great. I needed this product and it is a lot less expensive than the local aquarium store. Clear readout with the ability to calibrate and focus. Easy to use, easy to clean, easy to read.

Overall Score
5.0


(1 Points)

5. 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)

6. Automatic Temperature Compensation Sea Water Salt Salinity Refractometer for Aquarium, 0% - 10% & 1....

User Ratings: 50 10

Ade Advanced Optics Salinity10 First Impressions

"No assembly required."

I use this for my 10g brackish and it works ok. Like that it comes with everything needed. It is essential to get some specialized aquarium calibration fluid for 1. Looks to provide very accurate readings. I was surprise that the product was really cheap compare to the other ones. It is essential to get some specialized aquarium calibration fluid for 1. Hate the batteries, but once loaded, it seems to work fine.

  • Automatic Temperature Compensation Sea Water Salt Salinity Refractometer for Aquarium, 0% - 10% & 1.0 to 1.070 S.g. Dual Scale Hydrometer By Adeadvancedoptics
  • Manufacture: Ade Advanced Optics®
  • Product Dimensions: 8.7 x 2.8 x 1.42 inches; 6.4 Ounces
  • Editor's Impressions Of The Ade Advanced Optics Salinity10
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

Ade Advanced Optics Salinity10 Final Thoughts

"Easy to use."

Small problem with bubbles on the needle but other than that no issues. This one read perfect, and the others were completely inaccurate. Then I made a mark on it to set the salinity of my fish tank. Great product I used for beer making and my saltwater aquarium. Now that it's calibrated I love it! It's fast, it's tidy, and it's accurate. 026 and the tank isn't, new animals will go into shock.

Overall Score
3.9


(145 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
  • Quality
  • Value For Money
  • Affordability

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


(10 Points)

8. 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)

9. 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)

10. Coralife Energy Savers ACLAF877 Deep Six Hydrometer

User Ratings: 67 7

Coralife 100108103 First Impressions

"024 and my refracto read."

I found mine was calibrated out of the box. At first, I was getting bubbles sticking to the rotating arrow. Wipe down glass surface to dry it and put it back on the shelf til next time. So once your instant ocean shows a measurement. Does just as good of a job of any meter you would buy at the store! I tried it over and over and no bubbles! Simple to use, but if there are any air bubbles the results will be way off.

  • Coralife Energy Savers ACLAF877 Deep Six Hydrometer
  • Included components: All Components included in Picture and Description
  • Cora life is one of the markets leading manufacturers of premium aquarium products
  • Cora life's Hydrometer takes a true water sample at six inch depth
  • Easy to read and accurate, this specific gravity meter is designed to give temperature-corrected readings in warm water aquariums
  • Coralife is one of the market’s leading manufacturers of premium aquarium products
  • Coralife's Hydrometer takes a true water sample at six inch depth
  • Specific Gravity and Salinity PPT Scales
  • Optimal Specific Gravity / Salinity range indicator on scale
  • Manufacture: Central Garden & Pet
  • Product Dimensions: 6.69 x 0.79 x 4.72 inches; 3.2 Ounces
  • Editor's Impressions Of The Coralife 100108103
  • Accuracy
  • Quality
  • Value For Money
  • Affordability

Coralife 100108103 Final Thoughts

"Easy instructions."

I couldn't decide between this and one of the float arm meters or both. Once I figured that out, it works great. Now its easy to make sure I have the correct amount of salt in my aquariums. I use this for my 10g brackish and it works ok. My only criticism would be that it's a little too dark. I will update later to see if the refractor will keep its calibration. The instant ocean hydrometer will always be right.

Overall Score
4.3


(543 Points)

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