You know what . . . I think it is coming back! I see traces of it on a few pieces of substrate six days after the black-out.
If this continues I think I will treat the tank with the 1/2 dose of E.M. Erythromycin if it continues to appear. The person recommending this owns a fish shop and has used it with frequency and excellent success. I am relectant because of the small size of the DP's but I do not know what else to do . . . ANY SUGGESTIONS ??
I did start a 1/2 dose/day of the anti-biotic two days ago, the Puf's seem fine. The fish store owner told me to continue this 3-4 days until I do not see any of the blue-green algae/bacteria. Then he will help me clean the tank and we will install a magnum to assist in the cleaning process on the once/week cleaning. He thinks this will take care of it along with using a different filter.
To answer your question, I changed the light as I removed the black plastic from the tank.
Thank you for all your help and interest, I will keep you advised of how all of this progresses.