ATC refractometer reading in SODIUM CHLORIDE

[vashawn]

I bought a ATC refractometer from ebay. I chart is reading in sodium chloride and i dont know the conversion or how the read in salinity.
My red sea hydrometer is reading 1.024 and the ATC is reading the nxt long line under the 5

 

[mcgyvr]

Not sure if this will help.. http://www.texasbrine.com/tables/properties.html

 

[vashawn]

Im gonna return it and get the right one.

 

[nereefpat]

It looks like the one you got would work, but the range is a little funny. Our tanks are about 35ppt or 3.5%, so you want a refractometer that you can easily read in that range.


Have you tried putting a 35ppt standard in it? You should use this on any refractometer

 

[disc1]

A 35ppt seawater should measure the same refractive index as 36.5ppt sodium chloride. If you make up a 36.5 ppt solution of table salt and calibrate to that you can use any refrac you want.

 

[nereefpat]

Yep, you can absolutely make your own with table salt and a good scale.

David, to me the attached picture looks like the 3 &4% marks are awfully close. It might take some squinting to see if you were at 3.4 or 3.7, for example.