when I got it It was brown... is it normal for cp serum to be brown? because when i got on skin biology website it shows the cp serum is blue/green... will the effective of brown cp serm decrease? i just got it last month...

the label on the cp serum bottle said the mfg date is 4/11

Its not a problem. I notice some variations in color from batch to batch and its not unusual for the color to change somewhat over time.

They tested CP's 5 years old and found zero loss in effectiveness. So they will have full potency through at least 04/2016.