Algae Identification- please help

[Myka]

That's regular ole hair algae, not Bryopsis. Bryopsis is a type of hair algae that is feathery instead of grassy or like a green cotton ball. From the pic, yours doesn't look feathery. All nuisance algae are caused by excess nutrients in the water column. Sometimes old bulbs will be a trigger to start the growth, sometimes it just starts on its own, but it is always excess nutrients. Take a read through the link in my signature for all my suggestions to help get rid of nuisance algae.