Why this part lost its color?

[Notsolostfish]

My green slimer part of it, on the side have no color? Is that a concern. Or shading?

Alk:8.3
cal:410
Mag:1380
Phosphate:0.31
Nitrate:13
Ph:8.2

 

[Dburr1014]

Is it shaded?

Does it get blasted from a powerhead?