Help calibrating refractometer

[Tigerbarb]

So, my refractometer arrived this morning. To calibrate it, it says I need to put one or two drops of distilled water on the prism, close the daylight plate so that there is not a single air bubble or dry spot on the prism, hold the refractometer up to a light source, look through the eye piece, and turn the calibration screw untill the blue and white meet at exactly 0 on the scale. I got all of this done successfully, but now I don't really know what good it does. Is there anything else I'm supposed to do/know about?

Thanks.

[cocoa_pleco]

nope, thats about it and all i did with mine. distilled water has no salinity so it just sets the "bottom" point of the scale. now to get it measuring just put 2-3 drips of tankwater on the plate, close the cover, look into the eyepiece in light and read it. after, take a soft cloth, wipe off the water from the plate, and youre good to go

[Rue]

Yup...what Cocoa said...

[Tigerbarb]

Okay, thanks.

[kaybee]

For perhaps even more precise calibration, you can calibrate the refractometer with salinity calibration fluid, such as PINPOINT Salinity Monitor 53.0mS Calibration Fluid (fairly inexpensive at about $4).

This way calibration is performed against a known salinity rather than calibrating against 'no salinity'.