I have been seeking advice about the issue of decomposition of M Power and similar type products.
When mixed with pure water and kept in a closed container, M Power will still have a good "shelf life". However, if exposed to the air and/or mixed with "contaminated water" eg. tap water, "shelf life" cannot be reliably determined.
My posts above were therefore not completely accurate as this product could degrade in a couple of weeks or so or under more favourable conditions it would take considerably longer.
Safe and happy cleaning

Ken