The HydroTest COD System HTCOD is designed for the determination of chemical oxygen demand index (COD) using the small-scale sealed-tube method. The industry standard dichromate method can be considered as an estimate of theoretical oxygen demand. With a wide measuring range from 0 – 15,000 mg/L O2, the HTCOD is ideal for waste water testing, offering a small handheld photometer with two LED light sources housed inside a waterproof sample chamber. The highly-sensitive equipment is compatible with mercury-free tube tests, with optional chloride compensation to remove interference, and utilises the popular photometric determination method. Standard solutions can be used to verify operation and accuracy of the instrument. The thermoreactor is compatible with other products in the HydroTest range, and can also be utilised for tube test digestion of TOC, total Chromium total Nitrogen and total Phosphate. The thermoreactor operates at three pre-set temperatures, with three pre-set reaction times, and offers automatic switch-off functionality with audible alarm.