Hello Dissentasylum, its no problem to use peroxide.
Just mix it wel well with water.
If u use the 3% peroxide mix it with. 1 part peroxide and at least 1 to 3 parts of water.
It will clean your soil and kill all bacteria and fungus good and bad.
The extra oxygen makes the roots uptake more nutrients after watering.
Wear gloves do not touch the hydrogen peroxide.
And dont do it to many times.
Once in 2 weeks is what i would recommend.
U can also find info on YouTube and weedtube.
Hope this was an helpfull answer.
Keep om growing, Peace 👍🏾