The green terminator is a replacement for the CFT25 cartridge. The green terminator is reusable and easy to clean. The filter is a crucial component of any spa or hot tub system for removing dirt, debris, and other contaminants from the water. These contaminants can come from a variety of sources, such as skin oils, hair, and lotions. If left unchecked, these contaminants can build up over time, causing cloudy and discoloured water, as well as unpleasant odours.