i asked this a while ago i another thread , as i was frustrated with trying to get them as clean as possible.
guys recommended that you use some beach to kill off the stubborn bacteria.
i "hand wash" until i get them as clean as possible , and then leave then i water with some bleach over night.
next day i re rinse them in Ro water , to make sure beach is off.
bear in mind i do have about 10 socks , to make sure i dont have to clean like everyday