what are they and what can be done

[three dawgs]

You have to bear with me on this. I'm currently in Quebec and just got a phone call from a guy in Victoria. Heres the story.
He had a bad out break of algae(hair). So someone told him to keep the lights out. He has actinics which were running for about 6 hours a day. He just turned on his VHO and his tank is internally covered with clear and white looking aphids(this is what is described to me) He would like to know what they are and should he get rid of them and how. His tank is covered in them. Someone PLEASE help.