You can get an ATO Refractometer on Amazon for $20. Way more accurate. You use a sample of water on a lens then point the end at a bright light to see the reading. With a hydrometer, mine are accurate. But you need to make sure it’s on a level surface. And you always have to get that dang needle unstuck. Amazon is key for this hobby in my area. All of the LFS carry the same stuff at the same price. So I didn’t buy a refractometer for years. Because the LFS was $60 for the same one in the same case that I got on Amazon for $20. I’m all about buying local. I’m just not going to get ripped that hard.