I decided to purchase a refractometer because of the positive things I have heard about them on this site. I have been using a hydrometer for the past month and only started using a refractometer for the past week or so. My refractometer compensates for temperature and I calibrated it with distilled water. I have been using both the hydrometer and refracto in order to check my salinity in order to have a checks and balances system. Instead, my hydrometer( which I have used for a month, and I have fish, and other critters), reads 1.022, and my refracto reads at 1.025. I dont understand why there is such a difference and I dont know which instrument I should trust. everyone says that refractometers are very accurate and reliable, but I find myself trusting the 15 dollar plastic hydrometer, because I have been using it for a longer time and my fish seem to be doing well. The thing is, if I use the 1.025 reading, then I have to put fresh water in the tank in order to drop it down to 1.022. But if I do that and the salinity is really 1.022 to begin with, then I will end up with water which has less salt than needed. Any tips, trick, suggestions?