Additives for use in controlling pH. Liquid Silicon acts as a pH up but also strengthens plant cell walls, making for stronger flowering stems that are more resistant to pests.
H2O2 slightly reduces pH after a day or two due to buffer acids added to keep it stable. It is a good general purpose hydroponic disinfectant and adds oxygen to the nutrient solution.

N.B. Never mix pH up and pH down as they will form a precipitate that will completely gum your pumps up and damage your plants.