Hi, First of all, why ...

Hi,

First of all, why should you overdose gas chlorine? there are many reasons why perhaps if you tell us more. Also, the two things we pay close attention to in the parlance of water treatment are quality and economy in other words achieving the desired quality with minimal waste or minimal amount of chemicals. Remember Chlorine is a carcinogen.

Chlorine can and will  dissipate over time (especially gas chlorine) so one of your best bet is to allow it time to dissipate or if you're concerned with the taste it may give the water then pass it through activated carbon filters slowly..