Diatomaceous Earth is Blue/Green -why

Per other posting have been fighting liner stains all summer. FC has been maintained above 4.0 . Today thought time to open DE Hayward Filter and clean it DE earth had a bluish/green color to it which have only seen once before years ago . Is this a indication of anything ? I cleaned and added new earth and back up and running . Filter was working ok prior but normally I try to clean like this every 6 weeks since system as installed does not have a back flush option .

Using Bleach but have added some Black Algae treatment that was very blue in color?