You should never add a concentrated hydrogen peroxide solution directly to your reservoir. Always reduce the concentration first by mixing one part of the 35% concentrate with eleven parts of water.
So if you take one ounce of food grade peroxide, mix it with eleven ounces of water to get a 3% solution. Always use fresh distilled water if possible for best results.
The recommended amount of 3% solution of peroxide per gallon of water in hydroponics is around 3ml per liter or 2-3 teaspoons per gallon of reservoir water. Please note that we are talking about the diluted solution, NOT the 35% concentrated peroxide.
Just to be safe, when you start the dosage, add a little less than the quantity mentioned above. Your local hydroponics store may have diluted solutions and proper charts and instructions for mixing the stuff.
Each dose should last for around four days. When mixing nutrient solutions, it is best to add the peroxide to one half, and the nutrient to the other and then mix them. This will give you those bright white healthy roots.. Happy growing! 👊