Help a WC noob, why has my fluid turned yellowish/orange.

[Trigger5521]

While I had it apart lastnight I rebuilt my loop adding a EK RES, DangerDen fillport, and alphacool temp sensor. You can see here the res water is a little yellow, some left over fluid was in rad and ran into the RES after I completed the loop. Once I get my EK parts I'm going to flush again and go with black Fluid XP coolant. That Primochill Prue PC fluid is not doing anything for me.