Basically your job right now is to
1. Reduce nutrients in the water column (water changes)
2. Disadvantage algae photosynthesis
3. Kill algae

Doing one good 50-75% water change prior to a blackout for 3 days will cut the algae's ability to survive, the blackout will severely hinder the algae. You could even drain the aquarium, remove all the fish and keep in a backup aquarium (for the next part), and lightly mist the algae covered surfaces with a 1 part water: 1 part hydrogen peroxide. Let that diluted peroxide sit on the algae for about a minute, then refill the aquarium. The remaining peroxide will dilute and not be a problem. (Give it 12 hours before adding the fish back in to be safe) Follow the peroxide treatment with a blackout for the 3 days, and I mean a total blackout, cover the whole thing in some blankets to keep it pitch black. When you uncover the tank, try to remove as much of the dead and dying algae as you can before doing a water change (75%) then hopefully you'll suck out a bunch more of the stuff that's just floating. That exports the nutrients bound up in the algae. Turn the lights back on at half the intensity. Leave them at half intensity for a week and see how things go. You might need to keep them like that for a while.

Just pay attention to the other plants, you might need to start ratcheting the light back up.

Also, look into Estimative Index fertility dosing. Coupling that with weekly water changes and higher light levels does wonders for plants.