Hey, with the floating plants most of that light won't get into the water. Same as laying shade cloth over the glass.
Rex is right, the nutirients are low, you need traces and nitrate and K.
Some Tropica Master Grow or similar plus KNO3 will help. That's all it took to get my 10 gallon fixed after a month of medical treatments and no ferts. I had green hairy algae that was so long that the goldfish swimming in it twisted it into dreadlocks! I hoped the fish would eat it, but he didn't make a dent in it.
I almost tore it down, but was encouraged to try to fix it. So, i did large water changes and got the ferts in order, plus i added some amano shrimp to get into the fine leaves to clean that out. It looks fine now.