As I do not have a salinity probe on my system I have often wonder if what I am reading on my Chinese made refractometer is actually accurate. I find that the line on these units that indicated the specific gravity to be a bit fuzzy and what one person reads as 1.025, another could easily read as 1.026.
I do check the calibration of my refract weekly with the Fauna Marin Reference Solution but none the less a digital read out is a definitive value that is more easily repeated on each test.
So when I got the Hanna Digital Refractometer I just had to open it up and give it a test to see how close or how far off my testing really was.
I opened up the box and I was pretty impressed by how the unit looks.
I must admit that I handed the instructions over to Trina right away and instead felt the need to start pressing random buttons to see what happened
Here is a diff view with the unit in a position so that we can get to the good part and test some water!
After I had my fill of pressing buttons for the sake of pressing buttons, I stopped messing about and listened to Trina and what we were actually supposed to do with the unit.
So press the ON/OFF button and the screen will display the message above.
We used a pipette for the test, and as per the instructions covered the prism with water from our 144g half cylinder display tank.
Here is a picture with the prism surface covered with our water sample.
We pressed the read button and the unit almost instantly produce this value on the screen. As I was expecting a specific gravity value such as 1.025-1.026 to appear and as I had just tested the Hanna check and it counted down, I stood there for a few second half expecting the 34 to count down to zero and yield me a result
Then I realised that it was actually displaying Practical Salinity Units (PSU) and the machine had produced said value WAY faster than I had anticipated!
Now if you press the Range button on the right side the screen will briefly display the measurement units (in this case ppt).
Then it will change to the value and remain there.
Now to change to the value that I was first expecting,
And we are got exactly what I was hoping to see!
Here you can see what happens when we cycle back to the original screen of PSU
So to sum it up, the Hanna Digital Refractometer was crazy easy to use and getting results from this unit were almost instantaneous.
Very happy with the ease of use and quality of this unit.