I had a similar problem with one of my own aquariums. I discovered the light was being used for too long a period. I went without LED lighting for about a week and noticed a massive difference. The algae died back and I then introduced light again but for a shorter period. Also, I found the addition of fast growing plants helps. They seem to beat the algae to the nutrients and hold it back long enough to die out.
Since making these changes, I have not had anywhere near the algae I was seeing beforehand. I also removed the worse effected leaves.