Quote Originally Posted by [AK]Zip View Post
The impeller is blue. It is a dark blue since it seems the previous owner used dye in the water so it turned quite a bit darker.
Other than impeller color, one can examine the impeller hole inlet size to determine if it was indeed black or blue. The black impellers are the large inlet and the blue are a small inlet hole. Hopefully, the impeller was cleaned prior to testing since it rides upon the little ceramic ball.

Just my input here ... using dyes may have an effect on the impeller to the white ceramic ball in the pump housing. If the dye has any fine salt base, it would wear the contact areas of the impeller and the white ceramic ball. Even though Laing and the pump distributors are silent with what coolants or dyes to use, just be cautious on what is added to the liquids in your loop. Sure, dyes add the much needed BLING, but if not investigated first, could cost you your loop or hardware failures.