An acid neutralizing unit is used to offset, or equalize the high pH of a liquid. The pH of a liquid, soil, or other substance indicates whether it is acidic, neutral, or basic. The pH scale ranges from 0 (very acid) to 14 (very alkaline or basic). On the scale, a 7 is neutral, an acid is lower than 7, and a base is higher than 7. When an acid and base react, neutralization occurs. The result is a solution that is not as acidic or basic as the original substance. It is important to note that the pH scale is logarithmic, in other words, every one-unit change in pH represents a ten-fold change in acidity or alkalinity. For example, a pH of 6 is ten times more acidic than a pH of 7, while a pH of 5 is one hundred times more acidic than a pH of 7.
If manual backwashing is used, you only need to backwash if you see a significant pressure drop (at least 5 psi) across the filter unit. Keep in mind that some of these units have a pressure drop under normal operation and that an additional 5 psi drop as the media dissolves and settles is an indication that it is time for backwashing.
For example, the line pressure out of your storage tank maybe 40 to 60 psi and the line pressure on the house side of you media filter may range from 35 to 55 under normal conditions due to a natural pressure drop. When the house side operation pressure goes down another 5 psi, it is time to manually backwash. The lowest backwashing time that will restore normal operating pressure across the media is preferred. Two to three minutes should be adequate with a flow rate of at least 5 gallons per minute per square foot of surface media. While these are just basic instructions, a full reading of your product manual should suffice, as all products are made differently.