Polyphosphates sequester or react with metals such as Iron and Manganese and with alkali earth metals such as Calcium and Magnesium. Each type of polyphosphate exhibits a different sequestering rate for each of the aforementioned metals. Hexametaphosphate inhibits scale formation (through sequestration and crystal modification) caused by Calcium and Magnesium 20 times more effectively than pyrophosphate. And Pyrophosphate sequesters iron and manganese 16 times more effectively than Hexametaphosphate. Different waters require different treatment, some for scale, some for Iron and/or Manganese, and some for both. Blended Potable corrosion Inhibitors can contain several types of polyphosphates in addition to other materials. Each Potable Corrosion Inhibitor product will then have a different sequestering rate for each of the different metals or alkali earth metals. The Iron Sequestration graph illustrates the Sequestration of Iron for the different phosphates. If your water supply has iron then it would be advantageous to use a product that sequesters iron at a higher rate. A sale representative should be able to recommend the product that addresses all aspects of water treatment and one that will not only give superior sequestration but superior corrosion inhibition as well.