There are many schools of thought on disinfection. I go with the methods the government agencies use for cleaning drinking water. That is a bleach soak lasting long enough to get through any hard shells involved. Things like snails and their eggs? On tanks, I fill them, add a 1/2 to a cup of bleach and let it set at least overnight. The best bleach is the really cheap stuff without the scent like lemon, etc. i put anything else that I want to disinfect like hard filter items in the tank or let them run the bleach water through them. To get the chlorine out, drain and refill. That dilutes the bleach big time and then as you refill and add dechlor as normal, the rest is taken care of. A second way is to empty the tank and let it all dry. Chlorine is a gas which blows away as it dries.