Residual Chlorine (also ...

Residual Chlorine (also called Free Available Chlorine - FAC) is the ppm that remains in the water to prevent bacterial issues. Depending on the microbiological load within the water, you would dose in an amount of chlorine to kill off the bacteria or pathogens.

Example: you have to dose in 5 ppm to obtain a Residual of 1 ppm, therefore you have used 4 ppm to kill off the microbiological load. 

If this was a potable water application the dosing would allow a residual range of 0.2 to 5 ppm.

In respect of excess chlorine surely this would be an amount that is higher than the Residual you require for your application?

Are you dosing manually or using an ORP or Free Available Chlorine Controller and sensors?