Answer:
Dr.K.Y. kindly answered this question:
 
 
(Right photo: Legionella bacteria, from EPSCO with permission)
 
I will explain the point briefly. 
  
Does hydrogen peroxide really have disinfection effect?
Hydrogen peroxide acts both to disinfect and to remove slime. However, the degree of effect is dependent on how dirty the object is and on the concentration of the hydrogen peroxide solution. By the way, 3% hydrogen peroxide solution is a disinfectant known as Oxydol.
 
What is the relationship between the concentration of hydrogen peroxide solution and the effect of disinfection?
Because hydrogen peroxide oxidizes organic compounds, the effect of disinfection depends on the concentration of organic compounds in solution. Therefore, it is difficult to say exactly what concentration causes a specific amount of disinfection. I think that the organization of manufacturers of the 24hours–bathtub may have the standard value. 
  
Is a special license required to handle the hydrogen peroxide solution? Are there any concerns involved in using it?

Hydrogen peroxide solution is oxidant, toxic, and corrosive. It is designated as a poisonous substance in the Medicine Act in Japan,  and as “a hazardous substance whose information (name, etc) should be informed” in Industrial Safety and Health Law in Japan.
 
 
Acknowledgement
We would like to thank Dr K.Y. for his careful teaching and kind support for this answer.
  
  

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