Tryed the search...

[jck]

How long will chlorine last 6% 10.5 & 12. I know I saw it here so0mewhere just cant fined..

 

[257WbyMag]

It varies. What you need to remember is that the higher the concentration of sodium hypochlorite there is in solution, the less stable it is. So, storing 6% and 12.5% side by side, the 12.5% will lose its strength a little faster. If you keep it in a cool and dark place, the 12.5% will last you a few months.

 

[PaulR]

You are probably thinking about this chart of chlorine half-life based on initial strength and ambient temperature.
--paulr