The color of the propeller on nano streams is only cosmetic, the issue is that the blue propeller coincides with an upgraded disk 6055.740 which reduces clicking noise in and on off cycles. The disk is the main thing to upgrade but it does require a tool to remove it (small pick or small needlenose). I would get the pump and try it out, the noise is an issue for the user but does no harm to the pump, if you can live with it, you may just want to leave it alone.