Hanna Salinity VS Refractometer

[John Smith]

Howdy,

Happy Sunday all... I am having an anxiety attack over here... I was about to do a water change and decided to do my monthly calibration with my hanna tester. After calibrating my salinity of the tank was 1.023 and before it was reading 1.026 / 1.025. I panicked and grabbed my refractometer which reads 1.025 on the tank so I was like weird... I than tested my RO water which read zero salinity. I than decided to try the 35ppt calibration fluid from hanna to calibrate my refractometer which than shows my tank all sorts of wacked out.... I used another calibration packet and got the same results & than tried another packet from a different lot to find the same results... I don't know what to use and I am freaking out that my tank is completely the incorrect salinity.

I use a refractometer calibrated with natural sea water. I am guessing NSW might be more accurate than any calibration fluid.

 

[Tastee]

I will strive for consistency, however, knowing what the truth is, is helpful to keep parameters where they're supposed to... if your hanna says it's 1.025 but really 1.020 and you add new corals.. odds are they're going to die.

It doesn’t really matter which tester you use, as long as it is precise (i.e. reliably gives the same result given the same sample). Accuracy (i.e. reads the true measurement) is not that important. If you are adding fish or corals just make sure you test your bag water and QT/tank water with the same tester. When both read the same they are at the same salinity. Whether that’s ‘really’ (e.g.) 1.025 or not isn’t that important within reasonable tolerances.