salanity tester Aquarium Systems or Coralife Deep six

[redtang]

I have been using an Aquarium Systems sea test full range specific grafity tester for the last year. I recently went out and got a new Coralife deep six. Well, the old one reads my water at 1.024, and the Coralife reads it at 1.021, which one should I go by?

 

[barracuda]

What i have found when i was looking to buy a new hydrometer is that there are hard to find 2 with the same reading. Even from the same brand. I was looking for german made hydrometer. I picked up a couple and put them in the water. They gave me different readings.
What kind of hydrometers is considered to be most accurate?