I changed the thread title to this post to help get better answers so please do not be confused by it.

I have not read through it fully yet but i get this from time to time on my plugs, the hair algae is usually caused from bad made plugs. the slime sometimes is the zoanthid actually shedding its outer skin layer, leathers do this as well. a lot of times you can just scrape it off or use a turkey baster to blow it off if it is shedding enough. usually takes about 2 weeks to fully shed.