Salinity Refractometer for Seawater and Marine Fishkeeping Aquarium, Saltwater Pool, with ATC Function, Dual Scale: Salinity 0-100‰ and Corresponding Specific Gravity

This refractometer is easy to read. The contrast between the dark blue and white indication is vastly superior to any of the competition in this price range that have an "atc" stamped on them.

Everything is perfect with this, it’s not pricey and does the job

Good all

This loses calibration so fast that 1) you need to calibrate it with 35ppt calibration solution before EVERY use, and 2) it loses calibration so fast that you can't even trust the sample readings you get after calibration sometimes.Definitely don't trust it if you're calibrating to 0 ppt with distilled water. I would only consider using it if you immediately calibrate to 35ppt with 35ppt sea water calibration solution right before taking your aquarium test.I ran back to back tests with the same 35ppt calibration solution - cleaning with distilled water between tests - and 2nd test was already getting close to drifting 1 ppt lower than first test. And if you've had it sitting around a couple hours or a day, you're likely to be 3 or 4 ppt off from previous calibration.I'm guessing It's an okay tool if what you want to do is compare your tank water to your water change water and will be testing the tank and then immediately testing the water change water and just looking to see if they're the same. But with how quickly it changes its calibration, I don't put much trust in the actual number reading you get, unless you're okay being up to 3 ppt off. (which I would say is not an acceptable deviation).

Made of aluminum and easily rusts. Bought this thinking it was the same as my other refractometer, but noticed a weight difference. The heavier one was made of copper which is very resistant to rusting, while this one is made from cheap aluminum. Not just corrosion resistance difference, but strength and durability also. I can't recommend this one especially since it's being used for saltwater. If you keep this, be sure to wipe it dry after each use. All models that weigh half a pound is made of cheap material. Look for the ones that weigh 12 ounces.

its not blue and black. its blue and silver.