IceCap Salinity & Temperature Digital Pocket Tester

Salinity while sometimes considered secondary and often taken for granted is crucial to the health of our aquarium inhabitants. 

Generally, the specific gravity of salt water is around 1.025 or 33 parts per thousands.  While fish can tolerate swings that are higher or lower, most corals and invertebrates are far more sensitive and can stress if exposed to drastic salinity changes.  This is the reason why it is so important to make sure that your tank’s salinity is stable and when doing water changes, the salinity of your new water matches the water in the tank. 

Some hobbyist test their salinity by using a swinging-arm hydrometer but the problem is that they are hard to read and unless they are kept very clean, the floating arm will most likely render an inaccurate reading.  Most hobbyist use a refractometer.  Light will refract differently based on the salinity of the water.  The problem with refractometers is that they are hard to read, only work in a well-lit environment and they need to be calibrated.  Another instrument used for measuring salinity is a digital refractometer.  It uses the same principle as the refractometer but it relies on a computer chip to do the reading for you. 

IceCap, the same company that brought you the Smart RODI water filtering system and the Gyre 3K flow pump among many others, has released the brand-new Salinity & Temperature Digital Pocket Tester. 


This is a very handy, small and easy to use pen that can measure salinity as well as temperature.  Just submerge the tip of the pen into a sample of aquarium water and the pen will give you an accurate reading of your water’s salinity in three different units…

  • Specific Gravity
  • Parts Per Thousand and
  • Practical Salinity Unit or PSU

In addition to that, the pocket tester can also provide you with an accurate reading of your water’s temperature which is great to double check that your current temperature probe is reading correctly. 

The IceCap Salinity & Temperature Digital Pocket Tester works by measuring the electrical conductivity of the water.  It does not require for you to look through a small lens or stay completely still until the swinging arm stops moving. 

Simply submerge the tip of the pen into a sample of aquarium water and the pen will give you an accurate reading of your water’s salinity and temperature.

Although the pen can be conveniently tested directly into the aquarium we suggest the used of a large cup to protect the pen from electrical interference while testing. Since the tester measures conductivity, it is best if the water sample is completely isolated.  Aquariums usually have pumps, lights, heaters and other electrical devices that may interfere with the reading if you place the tester right in your tank.

To test - Turn the pen ON and then submerge the tip of the pen in the water sample ensuring that there is 1in space all around the sensor.  Give it a few seconds until you hear a beep and your tank’s specific gravity will show in a nice backlit LCD display.  There is no need to guess if the color change happens between the lines or if the lens is too blurry to even read it. 

Press and release the button once and you will be able to see your water salinity in Parts Per Thousand.  Press and release once again and get your water’s PSU and if you press and release one last time, it will display your water temperature. 

When done testing, just rinse and wipe the probe clean to ensure lasting accuracy and store it in the included case. 

Here are answers to some frequently asked questions:

My IceCap Tester is showing a different reading than my digital refractometer.  Is there something wrong with it?

No, actually while hard to believe, digital refractometers are NOT 100% accurate.  If you check out your digital refractometer’s user manual, you will see that they have an accuracy ranging of plus or minus 0.001 to 0.003 SG or plus or minus 2-3 ppt. The IceCap Salinity & Temperature Digital Pocket Tester has an accuracy of only plus or minus 0.001 specific gravity or 2 parts per thousand.

I notice that my temperature reading appears to be off and different with every test. Should I be concerned?

Not at all. Likely your room temperature or storage temperature was much lower or higher than the actual test sample. Place and hold the tip of the pen in the test water for 10-20sec and retest.

Is the IceCap Tester waterproof?

No, although capable of handling a splash or two, only the tip section of the probe is water resistant so please do not submerge the entire pen in water.

What kind of batteries does the IceCap tester use?

It uses two triple A batteries that can be easily changed by removing the lid at the end of the pen.


If you would like to learn more about the IceCap Salinity and Temperature Digital Pocket Tester, including detailed specs, beautiful high-quality pictures and replacement parts, head on over to  

Author: Carlos

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