Scale removal. These filters are 1/2 Polyphosphate, which removes the calcium from your water, and 1/2 carbon for removal of taste, odour and chemicals. Scale filters are recommended for use in all coffee machines, ice makers and steam ovens. They can be used for everyday potable water where it is uneconomical to install a softener. Pure polyphosphate cartridges can either be used as pre filtration or for non potable situations such as pressure cleaners and solar hot water systems.