Thank you for the feedback! The color that you see is a marker that is added to the material, and is not an indicator of the concentration of material. The color that shows up can vary quite a bit based on the directionality of the hose as well as the rocks. The dye does fade with the sun, so the shaded areas will also remain darker for a longer period of time. As always, the service is warrantied for 6 months for any returning weeds, so please contact us if you run into any breakthrough. Thank you!