A device to combat green algae. The UVC fluorescent tube is housed in a water-tight tube inside the device. The pond water inside the device is constantly exposed to UV-C radiation, which kills the algae germs in the water passing through. Be careful not to turn on the UVC for at least 2 weeks if you have added a pond starter or other product containing beneficial microbes to the pond. The unit can effectively de-algaze a pond with up to 10,000 litres of water. If there are no fish in the pond, it is sufficient for a maximum of 20,0000 litres. Note: The fluorescent tube in the UV-C unit should be replaced every year, even if it is still lit. When replacing the lamp, turn off the power, remove the old lamp from the socket and insert the new one. Be careful not to touch the new fluorescent tube with your hands. Touch it only through gloves or a cloth.