This is GSA. That's an easy one. Caused by low PO4, but also low CO2 plays a role. So bump up PO4 to around 3 ppm. But there's a delay. Even then it takes like two weeks before the algae stops growing, so have some patience. The old leaves won't recover, watch if the new growth stays algae free.
If it still remains, probably CO2 is too low, which could also be a cause here, because you're really using too much light on this tank. 2 bulbs is enough, at the most 3. Not the duration is the problem, but the intensity.
If you can't meet CO2 demand, algae is the consequence.
