You should already see a change in the mats, if a toothbrush is not affecting whats on the rock than most likely its going to be a macroalgae or coraline algae (calcium based algae). Also if you dont see any change in you mat one of two things is happening either its not cyano and its spirulina, or you are feeding your algae via nutrient source weather its the sand or your food all together.
For now lets get some pictures with whites up so we can see the color and texture.
You should already be seeing some changes in your mats. At the proper dosage I have not experimented on lower volumes of H2O2 if you figure 1 mil per 10 gallons has a large effect on bacteria in a system where is that threshold to where its no longer effective. Also insure that you are not feeding the bacteria. And lets get a pic of the tank with higher whites so I might be able to get a better understanding of what you are looking at.
