There isn't really a formalized written instruction, because it's not that high percentage of an intervention. But a common thing that works sometimes is 1mL of 3% H2O2 per 10 gallons system water 2x a day.
how it works is debatable.
it's enough for direct killing of some cyano cells, but not enough to directly kill dinos or GHA. But it is enough to change the oxidation state of some metals in the water (Fe etc) and this may be why some find it useful.