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High Precision Hydrometer - Tropic Marin

High Precision Hydrometer - Tropic Marin


Item #: TP65000

In Stock

High Precision Tropic Marin Hydrometer

Use this High Precision Hydrometer by Tropic Marin to determine the salinity of your aquarium water by measuring its specific gravity. This handmade instrument is designed to float vertically in the water and has a maximum deviation of 0.001 at 77 degrees Fahrenheit (25 degrees Celsius). It is an extremely accurate and reliable tool that can even serve as a reference point for other instruments. Best of all-- the Tropic Marin Hydrometer never requires re-calibration! 

  • Measures salinity with high precision
  • Never needs to be re-calibrated!
  • Can be used to fine-tune other equipment
  • Max. deviation: 0.001 at 77° F (25° C)
  • Scale from 1.021 to 1.031
  • Resolution: 0.0001
  • Handmade

How to Use:
Transfer aquarium water into a testing jar or cylinder with sufficient volume to fully suspend the hydrometer.

Ensure that your test water is at 77 degrees Fahrenheit (or 25 degrees Celsius).

Place the hydrometer in the testing cylinder and allow it to buoy. It is recommended that your hydrometer be centered and fully vertical for the most accurate reading. Take your reading from the level where the surface of the water and hydrometer intersect.

Manufacturer information

Tropic Marin
Tropic Marin: A strong foundation in science and hobby: The successful methods and techniques of today`s marine aquarists are the result of a close collaboration between serious hobbyists, scientists and specialists at public aquariums. Tropic Marin came about in exactly the same way over 30 years ago! This close cooperation resulted in one of the first complete one-part synthetic marine salt mixtures that provided the optimum natural environment for the professional as well as the private aquarist.

5 Stars


Reviewed on
May 11, 2020

Yes, I would recommend this.

Great hydrometer

Pros: High accuracy, simple, almost no maintenance, inexpensive

Cons: Fragile, need fairly still water which is at least 15 inches deep

I bought this as a backup for my Milwaukee digital salinity meter. After using it a few times, it's become my primary method to test salt content of my reef tank. I prefer this hydrometer better because there is no need to worry about calibration, replacing calibration fluid, varying light conditions, replacing batteries, or failing electronics.

The readings are very fast and the large scale allows accurate readings to increments of about 0.2 units (older, smaller hydrometers are more like 1-2 units which is not good enough).

You need pretty fairly still water, at least 15" deep. I pause water movement using my Ecotech Live app and then take a reading.

It comes with a nice storage case which you will need because they are fragile. The only care required is to rinse it off with tap water and wipe it completely dry with a paper towel each time you use it.

Sometimes old and simple is better.

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