But wouldn't that mean a week without anything breaking down?
That would completely depend on the extint of your "cleaning the soil" ....
In healthy conditions , the biology is all working together everyday after trans plant. As time progresses , they form the symbolic relationship needed to do organics.
So if everything is fairly healthy in the soil at the time you decide to use a chemical of some sort , then just the runoff of the chemicals is not going to hurt the biology much.....
If everything is healthyy in the soil and you decide to purposely sterilize it with peroxide (very bad idea) then in theory , the food that the microbes made availible before the "crash" is going to continue to feed your plant and with proper care , the soil will be good again in about a week. So a couple days of food left from prior to the crash should hold you over till you get your soil healthy again.
If this was me , i would use chemical food for a few days after the crash , then go back to normal in a week.