DD Refractometer

Refractometer specially designed for seawater salinity measurements ....

DD Refractometer

Refractometer specially designed for seawater salinity measurements.

• True calibration for seawater measurements.
• A new, finer scale division that runs from 20 to 40ppt salinity (SG 1,015 to 1,030).
• 20/20 calibration at room temperature for more consistency and accuracy in daily use.
• Full ATC (automatic temperature compensation) ranging from 5 to 30 degrees C.

More information about DD Refractometer

Almost all, if not all, refractometers that are currently available for the aquarium hobby are designed to measure "kitchen" saltwater (sodium chloride) and not "seawater". Although seawater usually contains sodium chloride, other elements such as magnesium and calcium are also present. And as a result, the refractive index changes, as a result of which an incorrect salinity value is indicated.

The most common symptom of this difference in the refractive index can be seen when producing seawater. Once the seawater has been prepared according to the manufacturer's instructions, it is possible that the levels of elements are lower than indicated by the manufacturer. In fact, all levels are too low because the salt content is not as high as the aquarist thinks it is. Most all have a low Ca or Mg for a certain SG, regardless of which brand of salt is used.

It appears that a 35ppt solution of real seawater has the same refractive index as a 36.5ppt saltwater solution. So when using a salt refractometer, the salinity will be up to 1.5ppt lower than desired. This is of course no further problem for the aquarist, but only if he is aware of the difference. After extensive developments, the new refractometer from DD solves this problem. This refractometer indicates, with the correct calibration, the true salinity and has a greater accuracy than was previously possible.