APHA = Pt-Co = Hazen = PCU = Platinum Cobalt Color

Bottles of APHA/Pt-Co/Hazen 500 color standard.

“APHA” stands for American Public Health Association Color Scale, the organization responsible for the original definition and implementation of this visual color scale as a standard method for rating water quality.

What is the relationship between the APHA/Pt-Co/Hazen and Gardner color scales?

The APHA/Pt-Co/Hazen and Gardner visual color scales were both originally based on liquid chloroplatinate color standards but have different history and intended use.

What Path Length Cell should I use for APHA/Pt-Co/Hazen Color Measurement?

FAQ: ” We are currently using a 10 mm path length and read in the 0 – 50 region for APHA/Pt-Co/Hazen Color, usually in the area of 10. Would you recommend a 10 mm path length with our equipment for this application?”