7
MEASUREMENT UNITS
Many methods were used to measure turbidity over the years. The Jackson Candle Turbidimeter was
used to measure turbidity as Jackson turbidity units (JTU). The Secchi Disk is commonly used to
measure turbidity in lakes and other deep waters (mg/L SiO
2
). Both methods are visual and are not
considered very accurate. To obtain more accurate readings a formazin based meter should be used
as a turbidity reading instrument.
The
HI98713
turbidimeter reports the measurements only in FNU (Formazin Nephelometric Units).
The conversion table between these measurement units is shown bellow:
JTU
FNU/FTU/
NTU
SiO
2
(mg/L)
JTU
1
19
2.50
FNU
FTU
NTU
0.053
1
0.13
SiO
2
(mg/L)
0.4
7.5
1
