The optoelectronic methods to analyze turbidity require an infrared light source or a white light source. All Lovibond turbidimeters are supplied with turbidity standards. Request information for additional turbidity standards.rrTB 350 IR modelr- Multipath 90° BLAC® sensor technology with innovative stray light removal and providing extremely accurate results for as low as 0.01 NTU turbidity.r- Maximum precision throughout the range, including 'fast settling' moder- Complies with ISO 7027r- Data logging and USBr- Color touch screenrThe use of the power supply (LO19820170) is recommended.rrTB 350 WL modelr- Multipath 90° BLAC® sensor technology with innovative stray light removal and providing extremely accurate results for as low as 0.01 NTU turbidity.r- Maximum precision throughout the range, including 'fast settling' moder- Complies with US EPAr- Data logging and USBr- Color touch screen