Yea, def getting a case of BBA......
suggest glut(Excel) till you can sort out the problem..
Looks a lot like my 55 in the recent past..
20mL of Excel per 55gal (some recommend as high as 1mL/gallon, currently using Metricide14 which is more concentrated than Excel @15mL/55ga/every 2-3days) every few days, a decrease in photoperiod (complicated by being exposed to ambient sunlight for me), and a bunch of Olive Nerite snails (cheap on eek bay) has it managed till I can find a
suitable cure..though w/ the window and wife liking sunlight.. it may be a bit problematic.
Most likely a wee bit too much light.
You're getting a lot of ammonia leakage out of old and dying leaves..
Next common recommendation is supercharge the plants w/ CO2 and ferts to outgrow the algae (well keep all plant leaves healthy, less leakage).
UNLESS you can sig boost CO2 I personally wouldn't recommend you trying it
Next a blackout.. BUT, obviously, would be only temporary at best I suspect (speculation, never tried one. Will leave it to others) unless you figure out the missing parameter.
You are in a stage I'd refer to as self perpetuating..until you find the cure.
algae on damaged leaves spreads to more healthy leaves, damaging them ect.. ect...
Just in case you take any of this a gospel.. be aware that my experience is NOT fully cured...but think I've learned how to manage it for the most part.
glut and Nerites are my "go to" for any algae problems..
Oh, and once the glut knocks it back, most plants will respond w/ growth..they are being stunted now..
not to forget, Glut is a carbon source as well..