The Hanna Instruments-96770-03 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate colorimetric measurements. These reagents follow the USEPA Method 370.1 and Standard Method 4500-SiO₂ C in which the reaction between silica and reagents causes a yellow tint in the sample. By adding the powder packets in the appropriate order, the reaction will take place and Hanna’s compatible portable photometer (Hanna Instruments-96770) will determine the concentration from the colour that is produced. The results will be displayed in mg/L (ppm) of silica. These reagents are designed to be used with samples that have an expected range of 0 to 200 mg/L silica.