Refractor

Never used one. I purchased one from Marine Depot. Its says to calabrate use distilled water. Can yo use ro/di instead ?

 

yes but it will be off. calibration fluid is what you want. I finally used my 35ppt and found out my water was 1.022 when it shows 1.025

 

Yes, that is preferred. I have the same one, mine will drift a little once or twice a month but it is a snap to calibrate with RODI unit. I would also suggest some kind of a lint free soft cloth to clean it with, kind of like what they use for eye glasses, you can pick that up at the dollar store amongst other places. You will like it, way better than a swing arm hydrometer!