Hello; I normally clean a tank after taking it down with a paste made from non iodized table salt. the salt paste does not scratch glass and is abrasive enough to remove a lot of water softened deposits. i mix very little water with some salt and rub it on the surfaces of the tank. i often allow the salt paste dry to a haze with the hope that it will dessicate most organisms in the tank. No real evidence than this does indeed kill all pathogens. It should take care of bacterial and fungal type organisms that are not in a spore state. A thorough rinsing may help to remove the spores after the tank has been dried well. The spore states can exist for a very long time waiting untill conditions are good and then become active again. All the equipment used in and around the tank will need to be disinfected or replaced as well.
I have read threads about disease control, perhaps a search will give you some pointers.
I have not used bleach my self, but seem to recall that others have posted about using it. The blue dye, metheleyne blue, has been used as an antifungal. It does stain some things blue, such as silicone and plastic tubing.