There are many options or blends of phosphates that are suitable to treat for corrosion. However, dry products are typically the most cost effective to administer.   Problems encountered with dry products are usually solubility issues. Sometimes, they can be difficult to dissolve. This problem can be easily corrected by making lower concentrations of phosphate solutions.   Small water systems may choose to purchase liquid products because of its ease of use and because they have limited resources for mixing. No tanks or mixing is needed to administer the product. However, three common draw backs for liquid products are: Reversion rate Water content Freight costs Typically, phosphate companies sell products by the pound. In liquid products, there is only 3-4 pounds of dry product in a gallon of finished liquid product. Savings for using dry products can be from 50% to 400%, depending on the supplier.