Regarding the white spots; this can also be caused by not removing all of the native oxide from the work, or waiting too long between cleaning and anodizing. "Native oxide" is the naturally occuring aluminum oxide film that forms on raw aluminum by exposure to air, kind of like rust on steel. The presense of this film will hamper anodizing or block it entirely. I see in your pictures that you aren't beadblasting, this is the fastest and easiest way to remove the film. You probably used sanding to remove the film; the white spots are shallow depressions in the surface where the sandpaper could not reach, these depressions failed to anodize properly since they were blocked. A strong alkai like sodium hydroxide (lye) or any other strong alkaline chemical will remove this oxide. I think simple green does, which is why Neilfj's cleaning method works, he isn't beadblasting either. Caswell anodize stripper would work well too. Desmut/deoxidizer is intended to remove this film, and is probably the best chemical method. In all cases the chemical should be used warm; between 100 and 140 deg. F. Through rinsing after this treatment before anodizing is essential.
I don't understand why you think you "aren't set up" to measure PAR; since your lab power supply has current and voltage meters/readouts, all you are lacking is a calculator (or a pencil) to do the arithmetic. If you just try it once you will know when to stop the process, you will immediately see the advantage and you will never anodize blind again.
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