That Color Isn't Right – What Went Wrong?

Accurate field-testing of water parameters is critical to preventing severe operational and biological risks in industrial cooling systems. Molybdate and iron testing often utilize thioglycolate chemistry, where proper pH control prevents mutual cross-reactivity. However, the presence of nitrite introduces a misleading orange interference that distorts photometric readings for both parameters. Failing to identify this interference can result in miscalculated chemical dosing, masking elevated iron levels and leaving systems under-protected against corrosion. Because dissolved iron acts as a primary nutrient for harmful pathogens like Legionella, undetected corrosion directly accelerates microbial growth and biofilm formation. Read the full paper to master colorimetric testing principles and eliminate chemical interference in your system.