Hey Jack,
Sorry for all the questions, I am trying to get an idea of what the cause could be. A picture would help determine the type of algae you have.
Algae typically can be caused by too much light, over feeding and/or high phosphates.
Ways to combat with great results: The first two are self explanatory, reduce light, feed less ( every 2-3 days ) test your water for phosphates ( tap and tank )
Do you have any otos? or other algae eaters?
Another thing is to add more plants to starve out the algae.
I had the bg algae and made the above changes and now I need to feed the algae eaters cucumbers or they would starve.
I hope some of these tips will help. There is no exact fix, typically it's a combo of the above mentioned.