One way to measure water transparency is done by using pieces Secchi (Secchi disk), which is a round pieces with a diameter of 20 cm made of zinc and painted white or black-white weighted. The tool is lowered into the water until it looks, its depth was measured, then lowered deeper. Furthermore, the chip is removed and when the puck back almost looked again, the depth is measured again.
The average price of the two measurements was taken as the brightness of the puck secchi. (Secchi disc visibility) by centimeters.
Figure 28. Measurement of brightness (a) secchi disk with the scale of measurement and (b) the use of disk secchi
Water depth measurement can use a stick-scale or large-scale meter rope hanging from the sampling location. when a depth of more than 2 meters it is advisable to use a rope scale. scale sticks can be made with a meter stick on a wooden stick.
Scale rope also can be made with the help gauge tied to the ballast. the goal is to use weights on the rope so that the rope does not drift and depth measured in an upright with the bottom waters.