Question: what instrument would you use to measure water clarity?
Answer: Silt Density Index (SDI) Testers. ... 
Pocket TDS Testers. ... 
Pocket pH Meters. ... 
Digital Thermometers for Testing Water Temperature. ... 
Pocket Combo-Meters Multi-Measurement Water Quality Testers. ... 
Pocket ORP Meters. ... 
Myron L Digital Water Quality Test Instruments. ... 
Myron L Analog Test Meters.