RSS Master Refractometer hot rod salinity measurement from Atago Japan

MASA Admin

8 May 2007
Reaction score
The Master Refractometer series by Atago is a high performance line of salinity measuring tools from Japan. We recently got some hands-on time with the Atago Master-S/MillM refractometer at the Bali Aquarium water monitoring laboratory, and it was quite refreshing to see a finely crafted salt-meter that isn’t just another aquarium company rebadge.

Before we tell you about the aquarium suitable models, it’s important to note that Atago makes a bewildering array of salinity measuring devices, from digital meters, to portable pens, traditional hand held refrcatometers and even in-line refractometers. Atago’s measuring tools are used to measure the salinity, specific gravity and refractive index for everything from blood to protein, soy sauces to urine, and of course the more mundane saltwater (brine) and seawater solutions.

When you do one thing and you do it well, it shows and this is particularly clear in the Master-S/MillM refractometer from Atago. When we first handled the Atago MillM it seemed very lightweight but a little more gripping and poking at the device revealed a very solid build quality.

The Atago refractometer has a very similar shape to traditional refractometers but it has a much larger refractive glass. This larger refractive surface translates into one of the clearest and sharpest readings we’ve ever seen through a refractometer with each level of PPT clearly visible in the viewfinder.

The MillM model in the Master S series is the manual version of seawater measurement which is calibrated for 20C/68F so users will have to refer to the included calibration chart to adjust their observed readings. The Mill-alpha refractometer is the refractometer model that automatically compensates for temperature so what you see in the viewer is the precise salinity of your seawater. This higher end Mill-Alpha refractometer also has a resolution of 0.5 PPT.

All of this high level refractometer action doesn’t come cheap with the Master-S/MillM refractometer retailing around $208 and the auto temperature compensating Mill-Alpha selling for just under $250. This is how much refractometers used to cost, but the rise of the reefing hobby has driven the cost down to consumer priced levels, but we have to wonder what compromises were made to get the price down to $40 for some of the cheapest models.

With so many models in their catalog, it would be a wet dream if Atago made a marine aquarium-specific model of their Master refractometer series, one with automatic temperature compensation, calibration at 25C/77F and with a scale that was restricted from 0 to 40 PPT. If that day ever came and the Atago ‘Mill-Aquarium’ model ever came true, and turned out to be an reliable tool for measuring salinity, we would gladly pay $200 for a really accurate measurement of the most important parameter of our reef aquarium water. [Atago]

[See image gallery at]

Readers also viewed:

Continue reading...