Does your loop have dis-similar metals like copper & aluminum? Some RADs are aluminum and a majority of water-blocks are copper. This would cause a cloudiness in the loop. You would need to do a flush while running the pump, BUT you have no RES to help you out there.
Any loop running dis-similar metals needs at least 30% PG or EG glycol and 66% distilled water to success work correctly to ****** the galvanic corrosion. (PS, this will not work if "long life" EG coolant is used, only the good ol' green stuff.)