If this information is true, God Bless you.
I've been dealing with GW for more than a week. I've tried water changes of up to 80% in my 29 Gal. tank (twice a week), but the water immediately turns green again. It's very frustrating. First it was BGA (which lasted more than 2 months), and now it's GW. Frankly, I'm getting a little tired. I would love to see a crystal clear tank with healthy plants and fish again, and do water changes just once a week like I used to.
Currently, I'm giving my tank a 3 day blackout just to see if it gets rid of it, but if it doesn't, I'll definitely try this out. Judging from your pictures, it worked for you. I just hope that it will work for me and many other people who seem to be experiencing this problem.