Poly forms are used for treating boiler waters and in detergents. In water they are transformed into orthophosphate and available for plant uptake. Organic phosphates are typically estimated by testing for total phosphate. The organic phosphate is the phosphate that is bound or tied up in plant tissue waste solids or other organic material.
Boiler Water Treatment Guidelines; Columbia Boiler Co
Phosphates are used to react with calcium hardness in the boiler water. In order for this reaction to take place it is important to maintain a pH at a minimum value of 9.50. It is desirable to keep the concentration of phosphates in the water to 30 - 50 PPM in order for complete reaction of the phosphates with the calcium hardness entering the boiler through the feedwater. Hardness