Editor's Choice - Our Favorite Exo Terra Aquarium Hydrometers
1. Exo Terra Terrarium Hydrometer
User Ratings: 66 5
Exo Terra PT2466 First Impressions
"Great product."Great product I used for beer making and my saltwater aquarium. I couldn't decide between this and one of the float arm meters or both. For the price you definitley cant beat this meter is great! However, the numbers are soooo small it is sometimes hard to read. 027, I'm so glad I bought this one and it came spot on. Does just as good of a job of any meter you would buy at the store! He is too cute not to want to take care of properly.
- Exo Terra Terrarium Hydrometer
- Wipe clean
- Analog hygrometer
- Adhere the hygrometer in the terrarium
- Clear analog dial display
- Easy to read and install
- Great for monitoring the humidity levels
- Manufacture: Exo Terra
- Product Dimensions: 0.5 x 4.1 x 7 inches; 0.64 Ounces
- Editor's Impressions Of The Exo Terra PT2466
- Accuracy [star rating='3.4']
- Quality [star rating='3.9']
- Value For Money [star rating='4.9']
- Affordability [star rating='4.9']
Exo Terra PT2466 Final Thoughts
"Great tool."I have a 2000+ gallon pond and I just put salt in it last month. Plus it is super easy to use and clean. Bubbles can greatly affect the reading. The water was at what I expected it should be. Does just as good of a job of any meter you would buy at the store! Simple to use, but if there are any air bubbles the results will be way off. Now its easy to make sure I have the correct amount of salt in my aquariums.
Overall Score
4.3
(1002 Points)

Here Are Some Other Related Aquarium Hydrometers
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
(8 Points)

3. 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 [star rating='4.3']
- Quality [star rating='5']
- Value For Money [star rating='4.5']
- Affordability [star rating='4.7']
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)

4. Pen Type Salinity & Temp Meter Measurement Units Checker Quality Tester ATC for Pond Pool Saltwater ...
User Ratings: 36 25
TEKCOPLUS SMTK-49_SOL First Impressions
"So here's the verdict."Just give me one simple, accurate reading to go by, and I'm happy. This is perfect to keep a check on the salt level in your tank. He is too cute not to want to take care of properly. Bought this as a back up refractometer. Get precise salinity readings in moments. The unit is really easy to calibrate and used. My only criticism would be that it's a little too dark.
- Pen Type Salinity & Temp Meter Measurement Units Checker Quality Tester ATC for Pond Pool Saltwater Aquarium Cooking Seawater Drinking Water (Salinity Meter 70.0ppt + Buffer Sol'n)
- Ideal for checking salt in fish tanks and aquariums, water monitoring, seawater-prepared food solutions, holding tanks and more!
- Measuring Range: Salinity: 0.00~10.0 ppt (NaCL) and 10.1~70.0ppt (NaCL)
- Auto Power-Off Function with disable feature
- °C/°F unit switchable ,Easy one-touch calibration, Waterproof Rating: IP65
- Calibration set: Buffer NaCI 50ppt and calibration guideline
- Manufacture: TekcoPlus Ltd
- Editor's Impressions Of The TEKCOPLUS SMTK-49_SOL
- Accuracy [star rating='3.8']
- Quality [star rating='3.8']
- Value For Money [star rating='2.6']
- Affordability [star rating='3']
TEKCOPLUS SMTK-49_SOL Final Thoughts
"Measurement does work."I have to recalibrate it ever use though which worries me sometimes. Just rinse with warm water afterwards. I bought this salinity meter for my aquarium. 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. Easy to use, easy to clean, easy to read. Compare it with the refractometer and adjust the refractometer so that it matches.
Overall Score
3.6
(5 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 [star rating='3.8']
- Quality [star rating='3.3']
- Value For Money [star rating='3.4']
- Affordability [star rating='4.5']
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. TOPINCN Square Saltwater Hydrometer Salt Water Salinity Meter Accurate Automatic Hydrometer Salt Wat...
TOPINCN First Impressions
"Super easy to use."Then I made a mark on it to set the salinity of my fish tank. This device is a godsend and so much easier and cleaner to use. 027, I'm so glad I bought this one and it came spot on. I would recommend you to purchase this and skip the other ones. This refractor should last a good number of years. Find a good light source to make reading easier. Just rinse with warm water afterwards.
- TOPINCN Square Saltwater Hydrometer Salt Water Salinity Meter Accurate Automatic Hydrometer Salt Water Salinity Meter for Fish Tank
- Accurate, durable, and easy to read sea water hydrometer
- This product is designed with an automatic level function, can automatically identify the level to avoid errors
- Very accurate measurement readings, please rest assured to purchase
- And each hydrometer has a laser engraved patent number
- Fit for brackish and marine aquariums. Perfect for testing both salinity and specific gravity of your brackish and marine tanks.
- Manufacture: TOPINCN
- Product Dimensions: 5.51 x 3.54 x 0.79 inches; 3.17 Ounces
- Editor's Impressions Of The TOPINCN
- Accuracy [star rating='4.2']
- Quality [star rating='5']
- Value For Money [star rating='5']
- Affordability [star rating='4.4']
TOPINCN Final Thoughts
"Case is nice as well."The refractor was off out off the box. It works OK but seems pretty flimsy and it's feel that way. I got this to have a more accurate read than the hydrometer. This device is a godsend and so much easier and cleaner to use. Bubbles can greatly affect the reading. Be sure to adjust the focus by turning the eye focal when you first receive. Ambient room light at night is not enough and makes what you're viewing dark.
Overall Score
5.0
(1 Points)

7. Ade Advanced Optics aaosal-B Automatic Temperature Compensation Sea Water Salinity Refractometer for...
User Ratings: 26 41
Ade Advanced Optics aaosal-B First Impressions
"Be well my friend."Comes with a nice carrying case for easy and secure transportation. I have gone two years in this hobby with a hydrometer. It says in the instructions to use distilled water. Good quality and simple to use refractometer. The refractor was off out off the box. It is heavy and easy to read in any light. I use this for my 10g brackish and it works ok.
- Ade Advanced Optics aaosal-B Automatic Temperature Compensation Sea Water Salinity Refractometer for Aquarium, 0% - 10% and 1.0 to 1.070 S.G. Dual Scale Hydrometer, Black
- Manufacture: Ade Advanced Optics
- Editor's Impressions Of The Ade Advanced Optics aaosal-B
- Accuracy [star rating='2.2']
- Quality [star rating='3.2']
- Value For Money [star rating='3.5']
- Affordability [star rating='3.1']
Ade Advanced Optics aaosal-B Final Thoughts
"Couldn't be happier."Would be nice if stem were slightly larger for easier read. Looks to provide very accurate readings. Works well on my Saltwater Aquarium. I've tried several different refractometers now and they are mostly the same. 027, I'm so glad I bought this one and it came spot on. I use this to check the specific gravity of my marine aquarium. I felt it wasn't accurate which was verified by my LFS.
Overall Score
3.0
(4 Points)

8. 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 [star rating='2.7']
- Quality [star rating='2.8']
- Value For Money [star rating='2.7']
- Affordability [star rating='2.7']
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)

9. 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
(99 Points)

10. Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automatic Tempera...
User Ratings: 80 3
Agriculture Solutions WL0020-ATC First Impressions
"Would buy another!"Very quick to calibrate and to use. I strongly recommend a refractometer vs. This is perfect to keep a check on the salt level in your tank. This device is a godsend and so much easier and cleaner to use. There are conversion charts and tables online. This requires repeatedly tapping the arm with a pencil. Great, I be had this b4 ez to test salt level.
- Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium 0-100 PPT with Automatic Temperature Compensation
- Measure salt water or salinity of water, ideal for aquariums and marine monitoring.
- Measures on 2 scales, Specific Gravity (D 20/20) and parts per thousand.
- Features automatic temperature compensation.
- Comes with hard case, dropper, screwdriver, user manual and cleaning cloth.
- The main part is made of chromium, it's very durable.
- Manufacture: Xin Da Cheng
- Product Dimensions: 2 x 3 x 8 inches; 8.8 Ounces
- Editor's Impressions Of The Agriculture Solutions WL0020-ATC
- Accuracy [star rating='5']
- Quality [star rating='5']
- Value For Money [star rating='4.8']
- Affordability [star rating='5']
Agriculture Solutions WL0020-ATC Final Thoughts
"Case is handy."Very easy, turn screw very slowly to calibrate. Used distilled water to calibrate, the screw is located under the rubber cap. It's a basic but reliable refractomer I use it for my aquariums. I don't want to deal with temperature correction or. Don't care much for having to post a review in order to activate warranty. Im using it for trying to create water conditions for amano zoes. Make sure to knock out the bubbles on the white dial by hitting it with your knuckle.
Overall Score
4.7
(1512 Points)
