Editor's Choice - Our Favorite Instant Ocean Aquarium Hydrometers
1. 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)
Here Are Some Other Related Aquarium Hydrometers
2. 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
(315 Points)
3. 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 [star rating='4']
- Quality [star rating='5']
- Value For Money [star rating='5']
- Affordability [star rating='5']
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)
4. Aichose Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium, Saltwater Pool, with AT...
User Ratings: 71
aichose SR0024BE First Impressions
"Easy to use."I use this for my 10g brackish and it works ok. I was surprise that the product was really cheap compare to the other ones. Make sure to knock out the bubbles on the white dial by hitting it with your knuckle. 010; I can easily read this off of the refractometer. I have a 2000+ gallon pond and I just put salt in it last month. I have a 2000+ gallon pond and I just put salt in it last month. It did not need adjusting to calibrate, though I tried to just to see how it worked.
- Aichose Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium, Saltwater Pool, with ATC Function, Dual Scale: Salinity 0-100‰ and Corresponding Specific Gravity
- It is designed for the measurement of seawater or low concentrated saltwater.
- Dual scale: 0-100‰ salinity and corresponding specific gravity 1.000-1.070
- Automatic temperature compensation function minimizes the effect of the temperature on testing result.
- Easy to Use: It's very easy to use even for new users. And no battery needed.
- Ideal for marine fishkeeping aquarium, saltwater pool, marine monitoring,lab,agricultural, gardening and educational purposes.
- Manufacture: XDC Co,.Ltd.
- Editor's Impressions Of The aichose SR0024BE
- Accuracy [star rating='4.4']
- Quality [star rating='5']
- Value For Money [star rating='5']
- Affordability [star rating='4.3']
aichose SR0024BE Final Thoughts
"Gave me confidence."I would like to provide a great marine environment for sea-fishes. It's perfectly accurate based on the known calibration fluid. I would suggest purchasing the salt calibration solution. Great little device to check your salt water levels in the swimming pool or spa. A hydrometer for making sure you have the right saltwater mix. I would like to provide a great marine environment for sea-fishes. I bought this and a hydrometer because of the reviews saying its not accurate.
Overall Score
4.5
(37 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. 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 [star rating='4.7']
- Quality [star rating='4.7']
- Value For Money [star rating='3.5']
- Affordability [star rating='4.8']
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)
7. 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)
8. Digital Salinity Tester for Salt Water - Aquarium Salinity Meter with ATC, IP67 Waterproof, 0-200 PP...
CIZTADA First Impressions
"Works great for reefing!"Functions just as it is supposed to. Looks to provide very accurate readings. Waterproof if you accidentally drop it in the pool. Does just as good of a job of any meter you would buy at the store! I have a 2000+ gallon pond and I just put salt in it last month. Comes with a nice carrying case for easy and secure transportation. Good quality and simple to use refractometer.
- Digital Salinity Tester for Salt Water - Aquarium Salinity Meter with ATC, IP67 Waterproof, 0-200 PPT Large Range Multi-Parameter Tester for Seawater, Fish Tank, Hydroponics
- [Large Salinity Range] Ciztada salinity tester has 2 measurement modes, scale range: 0~9999 ppm/10.0~200 ppt and 0.00-25.00%, which is 2 times than the salinity refractometer
- [Automatic Temperature Compensation] Ciztada salinity tester is equipped with ATC part inside, during normal temperature, once calibrated, the temperature change would never affect the accurate of your measuring result. This makes it more convenient to use in different temperature
- [Easy Reading with LCD Backlight] There is no need to worry about seeing the displayed value if the light is insufficient. Ciztada salinity meter features a green backlit LCD to help you see the measurement results clearly in any situation
- [Multifunctional Salinity tester]: The Ciztada multi-parameter Tester can test Salinity, TDS, EC and Temperature in an accurate, quick and reliable manner for most regular water solutions' testing. Support One-tap switch from salinity to TDS/EC
- [Wide Applications]: Measures saltwater or salinity of water, ideal for aquarium, marine monitoring, salty pools & spas, koi fish pond, hydroponics and etc
- Manufacture: CIZTADA
- Batteries: 3 LR44 batteries required. (included)
- Editor's Impressions Of The CIZTADA
- Accuracy [star rating='5']
- Quality [star rating='4.6']
- Value For Money [star rating='4.6']
- Affordability [star rating='5']
CIZTADA Final Thoughts
"Accurate so far!"Too that makes it appear too cheap. It says in the instructions to use distilled water. This is perfect to keep a check on the salt level in your tank. Normally that gives the more accurate reading. Once I adjusted the refractometer, my aquarium salinity read 1. Bought this one to check my old one, this one checked right on the dot at 1. Bought this one to check my old one, this one checked right on the dot at 1.
Overall Score
5.0
(1 Points)
9. TRZ Salinity Refractometer for Aquariums, Marine Monitoring, Saltwater Testing, Dual Sacle 0-100ppt ...
User Ratings: 58 7
TRZ Hamh Optics&Tools First Impressions
"Using for my Pacman frog."Plus it is super easy to use and clean. Very quick to calibrate and to use. I bought this refractometer as a more accurate option for salinity than a hydrometer. It works, we'll i assume it does as i have nothing to compare it to. I think those reviews just didn't know how to use it properly. Do not spend money on calibration fluid to calibrate this meter. I've tried several different refractometers now and they are mostly the same.
- TRZ Salinity Refractometer for Aquariums, Marine Monitoring, Saltwater Testing, Dual Sacle 0-100ppt Salinity & 1.000-1.070 Specific Gravity Automatic Temperature Compensation.
- It is more accurate than a hydrometer and easy to measure. Designed for the testing the concentration of salt water and brine, perfect for use with aquarium Marine monitoring and quality control in scientific research and clinical laboratories
- Measurement range: Salinity 0 - 100 ppt, (0 - 10% salt content), SG 1.000 to 1.070 SG, Resolution: Salinity +/-1 ppt; +/-0.001 SG
- Easy to use. Place 2 drops sample on the main Prism and close the panel and hold the refractometer up to the light and look through the eyepiece.
- The refractometer's body and the retaining ring are made of brass and chrome plated. The internal optical lens with high refractive index make up the precision optical system.
- Please ignore reviews from Diver. This commentator has a suspicion of being hired. Seller opponents use unfair means to compete!
- Manufacture: Hamh Optics&Tools
- Item Weight: 5.6 ounces
- Product Dimensions: 7.48 x 2.17 x 1.38 inches
- Editor's Impressions Of The TRZ Hamh Optics&Tools
- Accuracy [star rating='3.3']
- Quality [star rating='4.6']
- Value For Money [star rating='5']
- Affordability [star rating='4.1']
TRZ Hamh Optics&Tools Final Thoughts
"Be well my friend."I found mine was calibrated out of the box. Good quality and simple to use refractometer. I was surprise that the product was really cheap compare to the other ones. Works well on my Saltwater Aquarium. Don't care much for having to post a review in order to activate warranty. Compare it with the refractometer and adjust the refractometer so that it matches. When I compared it to what my local pet store was reading my water at it was dead on.
Overall Score
4.2
(112 Points)
10. 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)