There is a "foam" floating on surface while tempering

Hi, with my latest batch of cacao powder and butter, I have noticed a "foam" that floats on the surface of the chocolate while it is being tempered. It is bubbly, but very small bubbles in texture, can be skimmed off the top till eventually it is gone, but if left ruins the bars. I skim it off the top, and the bars are ok, but it is a lot of work, as it requires skimming for perhaps ten minutes, and wastes a lot of product.  If I leave the foam, the bars have spots on the tops of the bars when removed from the molds. Any ideas as to if it is the powder or the cacao butter that is the issue? The powder has clumps in it when I open the bag fresh, and newly delivered. These are 14 kilos bulk bags from a respectable wholesaler. Should cacao powder be considered acceptable if it has clumps and lumps? I have tried to upload a photo, but I can't figure out the extension acceptable on this site. tiff, jpg, jpeg and pdf don't work.

Hi again, this time it looks like it accepted my photo, yay!

Foam Cacao4.pdf  •  1.4MB