Icecap Digital Refractometer issue

davejep · Apr 19, 2018

So after watching the video and finding that my local store had some in stock, I decided to pull the plug and grab one.
I have an issue with the reading I am getting.
I have three different refractometers that I have collected over the years.
All three have been calibrated using standard seawater saline at 35ppt.
All three refractometers give a reading on my water at 1.o27, just a bit high but all three agree on same reading. With the new digital icecap I get a reading of 1.021
A buddy is getting the same result with his as well, a bit perplexed.
When I get three different devices all giving me one reading and the other giving me a different result, I want to lean the way of the Icecap being the one that is wrong.
Any thoughts out there?

Reefing Madness · Apr 20, 2018

dragon99 · Apr 20, 2018

I'd trust the refractometers.

I use a milwaukee digital refractometer, it reads 2ppt higher than my calibrated refractometer and Apex probe. However, it's consistent and much easier to use so I've just accepted that if I get a 37ppt reading with it that it really means 35ppt, and my salinity is where I want it.

JCTReefer · May 3, 2018

I finally receive the salinity meter after a month of waiting.

I was supper anxious to test the accuracy of it. After unboxing, I calibrateed my BRS ATC referactometer using aquacraft 35ppt calibration solution. Before calibration I measured the temperature of the refractometer and the temperature of the calibration fluid with an infrared temp gun. Both were at 77 degrees Fahrenheit.... I know it supposed to be ATC, but we keep the house at 65 degrees. This makes a huge difference when calibrating. So, I let the instrument and fluid warm up before calibrating. The refractometer read 1.026.4

After that I tested my tanks water. It read 1.026.4 … So there was my base line for testing. Next I did my first test with the meter and the scoop like the instructions said. The reading came out to be 1.024.. I tested the tank water a dozen times with the scoop and it consitently read 1.024. So atleast it was consistent! But still out of the +/- .001 accuracy range stated. I then decided to see what would happen if I tested without the scoop.. I tested probably a dozen times directly in the tank and it read 1.025 consistently with the pumps running. I then read there could be electrical intereference from pumps and such so I tested without the powerheads on. It consistently gave me readings of 1.025… I would think flow would be better for conductivity, but I'm not possitive on that.. After this I tested calibration fluid. I squirted enough fluid in the supplied scoop to top it off and took a measurment.

The calibration fluid measured 1.027 consistently. Then I decided to pour the calibration fluid in a small shot glass and see if there was a difference. Surprisingly it read 1.028-1.029…. Then, I decided to test my tank water in the same shot glass without the scoop and it read 1.025 consistently. So pretty much the same reading without the scoop when testing the tanks water directly and in the shot glass.

I honestly think this thing is more accurate without the scoop when testing. Between each of the test, I rinsed the meter with RO and wiped dry with a microfiber cloth.
Update. Been using this thing for a while now and it has very consistent readings. I never use the scoop when testing. For my particular meter it reads .001 low.... So I just add a thousandth. If it says 1.025 it's actually 1.026 Easy enough.