Token,
Try this simple recipe: Scrape the back thoroughly with an algae scrapper; remove as much as you can. Do a 50 percent water change, yes 50 you will be okay. Then don't feed your tank for 3 days straight, just walk away on this part, trust me.
I believe your problem is way too much nutrients in this tank, it's not just the lights that are triggering the algae, they need nutrients and they are getting it from the water.
If you cut the nutrients suddenly and scape the back you will start to turn the tides to your favor.
On the third day, start to feed your tank but cut down on rations only what can be eaten per feeding.
If you don't have any red hermit crabs purchase just three medium to small sized ones and drop them in. They are more nocturnal but they will start to work on that algae that you don't see in the back.
Let me know how it goes?
MG