How long have you been using the purigen? Have you had to recharge it yet?

How do you know when to recharge it? Its supposed to change color, but how dramatically?

I don't have the original packaging so was just searching for instructions. Some recommended pure bleach and some said a dilution. I've been soaking it in heavy prime and it still smells funny... but not like bleach. I'm a little paranoid to stick it back in my tank.