The pH of the nutrient solution in hydroponics is interesting. If you should find it necessary to raise the pH with Potassium, you should be aware that it takes a while for the pH to change because of the buffering of the organic molecules like the Phosphitides and Blackstrap Molasses. The pH will tend to drift toward acid, so maintain a pH between 6.2 and 7.8 through the addition of dilute Potassium Hydroxide. It is especially desirable to add oxygen when using organics. It is important to keep down anaerobic bacteria and fungus.
Chemicals can very quickly produce organics in the presence of light and water.
The hydrogen peroxide is dissipated within 24 hours, so it should be replenished daily in a hydroponic system. Oxygen is beneficial to the plant root zone for many reasons. If you put a lot of peroxide in at a time, it can lead to floating clumps of rockwool and other organic material. If using drip or aeroponic irrigation, I d suggest using a good water filter attached to the pump which supplies the nutrient water. It would be ideal to not recirclate the nutrient water.