自Dupla在欧洲以外的礁石业余爱好中挥舞着狂潮，但其新的Dupla Marin比重计（一个新的高精度和准确的比重计）可能会将它们重新回到地图上。您可能会问自己：“当我使用折光仪多年时，为什么我需要一个比重计？”但是近年来，我们对长期使用和维护轻型盐度测量工具的误解存在严重的误解。
The Dupla Marin Hydrometer is a large glass floating hydrometer which is hand-calibrated with tiny weights to achieve a very accurate reading of specific gravity. The measurement scale of the Dupla Marin Hydrometer is proportionally large as well allowing precise measurements of salinity to within 0.2 ppt – no swing arm hydrometer or analog refractometer can read anywhere close to that.
It may not be practical to use the Dupla Marin Hydrometer for an everyday salt testing tool, but instead its real calling may lie in serving as a reference tool for calibrating other hydrometers and refractometers. At a given temperature, probably 25C (~77F), the accuracy of the Dupla Marin Hydrometer should be about as high a level hobbyists could ever hope to achieve, allowing proper measurements of one of the most crucial parameters for life-supporting seawater in aquariums.
The kind of hand-crafted, hand-calibrated glass Hydrometer the likes of which Dupla Marin is offering won’t be cheap. Like PAR meters, the Dupla Marin Hydrometer is exactly the kind of seldom-used but high value equipment that an LFS or aquarium club could invest in for the benefit of their customers and club members.
