hydrogen peroxide is probably the last thing you want to water into your organic soil, I know those who say small amounts improve o2 and all that but the bacteria and fungi in the soil is what you want there, organic living soil....IE living food/soil web....you will have to reinoculate your soil after doing this so why bother, there is NO NEED to kill anything in your soil aside from pests like thrips or fungus gnats etc.... IE bugs... Go ahead and piss off the microherd in your soil with something like hydrogen peroxide or even worse H2o2.... watch how long it takes to get your plants looking nice and healthy again, even worse do it during bloom so your yield will suffer because you loose time trying to reinoculate your soil so your plants can have the proper nutrition to do what they need to in order to produce those beautiful organic crystally nugs.....
The other thing is no matter what kind of nutrition you are giving your plants, you do need wet and dry cycles. The more you let the soil dry out, the more elaborate of a root system the plants are going to build because they only go looking for water/food when they can no longer get it where they lie...... so you can water your plants too much without over watering.... When you water your plants to soon (without over watering) the roots arent traveling around the pot looking for water/nutrition.... Why do you think the roots eventually find their way out through the holes in the pot....they are chasing the water...... the larger more elaborate root system, the larger the buds and the healthier root zone/overall plant..... Its not wise as it was said above to let the pot completely dry out, a moisture meter as said above is a good idea for newbs, however if you fill the pot with soil before you put a plant into it should give you a fairly close idea of how that pot will feel without any moisture give or take the weight of the plant. Something I do even though I dont like doing it with organic soil (because disturbing the soil is disturbing the microlife) is to stick my finger into the outer edge of the pot, if I get 2 knuckles in and dont feel any moisture its close to watering time based on how heavy the pot is, it can be stretched a bit as well as long as the plants arent going to fall over dead because they are too dry.... If you do some reading into the veganics thread at the top of the organics forum, matt rize suggests letting the plants literally get to the edge of death before watering for the reasons I stated above about the plant needing to constantly continue building and improving the root mass..... If you want nice white healthy roots, use an enzyme like hygrozyme....dead roots will become food for the microlife in the soil as they decompose so theres no need to clean/kill them with peroxide....
And please... if you like having a healthy living soil/food web going on in your plants root zone... leave the hydrogen peroxide for cleaning cuts on your body and h202 for the hydro guys who need a sterile root zone...... Ohh... and you can use the peroxide to sanitize your compost tea buckets and air stones...... so think what it will do to the microlife in the root zone of your plant....