Are you really sure that you are using the same chemicals? You may be using the same brand bought from the same store but you really do not know what is in the container.

I have noticed "increased stink" on my Arctic head also. My guess is that the blue stuff I use has been reformulated. There has been steady pressure on the makers of these type of products to make their products more green. Although that is good for the environment, it does not necessarily make them more effective.