on February 27, 2018
I have not had any issues with this refractometer so far.
I like it but have to calibrate it about every 2 weeks.
on February 16, 2017
Seems to need constant calibration, I use a reference sample (Two Little Fishies Accurasea) at 1.025 just to make sure its on point.
Not a good rs product.Maybe I was unlucky but my refract. was showing 33ppt and in reality I had 37 in my tank. Bad readings all time and I had to calibrate it to every measurement.I ask for a refund and I obtained it but I can't recommend. I gave 2 stars for the refund.