Refractometer

[jswinberlin]

I received a refractometer today as a gift. It shows brix percentage so I was a little confused. Looks like proper salinity would be between 4 and 5%. Is this the wrong instrument or is there a better one with a scale designed more for marine aquariums?

 

[Mandarin66]

Maybe this will help?

Specific gravity

http://www.americanmarineusa.com/salinityconversion.html

Maybe 2nd one is better lol

 

[Bifferwine]

I received a refractometer today as a gift. It shows brix percentage so I was a little confused. Looks like proper salinity would be between 4 and 5%. Is this the wrong instrument or is there a better one with a scale designed more for marine aquariums?

Hmmmm the refractometers I've seen for the hobby have two scales (one on each side), with 1.000 to 1.070 on one side, and the equivalent percentage on the other.

Does this picture help at all?

Marine Depot Aquarium Refractometer

 

[ccCapt]

35 ppt is about 4.4% Brix. This article may help.
Refractometers and Salinity Measurement by Randy Holmes-Farley - Reefkeeping.com
"A commonly manufactured type of refractometer is called a Brix refractometer. Its scale usually reads in Brix, or % Brix (percent Brix). These refractometers are used in many industries to measure the concentration of sugar in water such as in the soft drink industry. They can be used to measure seawater's salinity, but are not always precise enough around the range of seawater's refractive index to be useful. A resolution of 0.2% Brix is common, and that is borderline acceptable for the reasons detailed below.
Table 4 shows the relationship between seawater salinity, refractive index and % Brix. If a refractometer has a resolution (not accuracy, but resolution, which is the finest amount it can distinguish) of 0.2 % Brix, then that translates to about +/- 1 ppt. So the best resolution would translate to 35 ppt seawater reading 34-36 ppt, which may be adequate for reef aquarists. A Brix refractometer that reads 0 to 10 % Brix with a resolution of 0.1% Brix might be a fine choice for determining seawater salinity in a reef aquarium, (although they are not inexpensive). Some Brix refractometers have a resolution of 0.5 % Brix or even 1% Brix, and they would not be suitable choices."