Can scraping a large amount off algae off the glass hurt your aquarium?

You added a great deal of nutrients to the system and dislodged a lot of debris which is most likely why your anemone and leather acted that way.

Clean your sump, tank and refuge thoroughly of detritus to eliminate food for the algae. Hair algae is soft and flows in the current, bryopsis is brush like and stiff.

 

Could the change in seasons possibly have caused some direct sunlight to reach your tank at some time in the day?

 

Yes I have about an inch and a half to two inch sand bed

 

No the tank Isn't near any windows

 

Did another water change tonight and brushed some more off the rocks tonight and it came off easier. I may slowly be winning . Still seriously considering a few additional powerheads

 

FWIW I have (2) 750's and (2) 1050's on my 55. I definitely think you could use a couple more powerheads.