Color Scale

The Forel-Ule Scale is a simple tool to approximate the color of bodies of water and is used in limnology and oceanography. This measurement requires a Secchi disk (30cm in diameter) and the FUS colour scale/palette which has 21 different colour bars ranging from indigo-blue (index 1) via green (index 10) to cola-brown (index 21). The Secchi disk has an attachment mount to connect a weight and rope. The color of the water body is compared to the Modern Forel-Ule scale colour palette while being held above the Secchi disk at half the Secchi depth. The result is a color index for the water body which can for example be used to identify gross biological activity. The Forel-Ule Scale palette works best with a Secchi Disk. If you do not own a Secchi Disk we recommend buying the complete Forel-Ule Scale Toolkit.