i think you would do more damage cleaning a bucket reservoir with bleach than just dumping your nutes and giving it a quick rinse. bacteria in a reservoir is a good thing for the most part
I only use bleach between grows and actually there is some other stuff I prefer to use, P20 or something like that. H202 is good for getting rid of powdery mildew and seems to work if you soak your seeds but I wont add it to the res
