Bacterica in Condensate

Good day, Have a large steam system 3 60+ HP boiler running 100# steam to a campus.  2 outside loops for steam and condensate.  Chief of plant has found Fibrorous (sp) red iron bacteria in the renurn.  it is believed to be on only one of the loops, it is showing up in the DA tank where it subsequently dies and clogs strainers valves and just about anywhere it can rest.  They are checking for an agent to mix into chemical feed to battle the growth.  Anybody got an idea??