These days, a plethora of digital salinity monitors/devices are available on the market. From controller companies offering probes for our controllers to great testing companies like Hanna and Milwaukee (which has been my trusty go to salinity monitor for years) there have been units out for several years now, and I have been pleased to see the monitors evolving to make things much more convenient for us end users. Icecap started the trend in North America with the digital pocket salinity monitor, which made the unit much more portable and easy to use. I always say that if it’s easy, people will use it and I think it’s imperative for us hobbyists to have a good refractometer and to be able to check from time to time to make sure that our salinity is where it’s supposed to be. The Salinity Pen Plus+ model from Poseidon recently caught my eye, and this is my experience with the unit.

Right off the bat, I noticed something different from the current line up of digital salinity pens. This unit has calibration fluid. This is actually very good for me and it should be good for you as well. Why is that? Because how do you calibrate if your readings are off? I think this is an excellent inclusion from Poseidon. Instructions are easy to comprehend and illustrations are always a nice touch for simple people like me. It’s very straightforward, but you have to follow the directions, so be sure to give it a quick glance before you dive in.

You can see the calibration fluid here. This solution, when properly calibrated, will read at 30 parts per thousand (ppt). After you calibrate it, store it in safe place at room temperature as you will need this again. The company recommends that you calibrate before any use but from my uses over the week, I haven’t noticed any changes in value. Not that I’m recommending this, but I was surprised at how well it held the calibration. Regarding the calibration fluid, some may wonder if it’s ok if a minute amount of it gets into your aquarium. I contacted the manufacturers and they have told me that it is laboratory verified saline solution, so you don’t have to worry about any kind of harsh chemicals entering your aquarium.

How to make sure that if this is accurate? Unlike any other elements, you don’t need to send your water to a lab to get accurate readings. For me, the easiest and fastest way to find out is to test it against the lab grade reference/calibration fluid. I know it comes with one, but I always like to reference it with a 3rd party brand that I know and trust. I always have one available and my choice is  Accurasea from Two Little Fishies. It’s 35ppt at all times so I use this as a reference guide with any refractometers that I use.

Here is the test! The unit’s LCD display shows Salinity (ppt), Specific Gravity (SG), and Temperature (Celsius/Fahrenheit). One thing that I did notice is that it rounded my number up. My Hanna showed the reading at 35.7 ppt and on this unit, it rounded up to 36 ppt. Not a deal breaker at all but something to take note of and decide if this is ok for you. I tested 3 times in multiple different occasions and it gave me the exact same results each time, so consistency, which to me is the most important aspect of any test unit, was definitely there.

Tip/ Advice : I confirmed with the manufacturer that the whole metallic probe part is plated with platinum and this is what they told me. “The electrode itself is very susceptible to corrosion and pitting of the platinum surface. Care must be taken to rise off the saltwater and properly dry the unit before storage.” Be sure to rinse with freshwater, dry gently, and use the cap that they give you.

My take. 

Its price of $109.99 is very competitive in the world of digital salinity refractometers. Some are actually double that price. Ease of use, and the inclusion of the ability to calibrate as well as calibration fluid, make this unit a new power horse in the field. It does estimate upwards on your readings in ppt but can easily reference back to specific gravity to see where you are at. I think this is one of the better handheld devices that I have tested, so if you are in the market for a reliable digital refractometer, this is a unit that you should look into before making the final decision.

It’s coming to U.S. in few days and you can order it here.

Happy reefing!