Osram Puritec HNS 25W G13 G25T8. This is a ultraviolet or germicidal lamp. They are used in air and water disinfection systems. Common applications include Aquaculture, Air Conditioning and Private Water Supplies. These lamps should be replaced every year or after 9000 hours as the amount of useful uv-c light will diminish after this. This ensures high system efficacy and maximum security of disinfection.