Best way to fight algae is to have a large and healthy plant mass.
With healthy plants, they fight the algae for you and the amount of healthy plants in my aquarium directly correlates to how much algae my tanks get. (light intensity/co2/ferts all in good levels)
Your original setup didn't have much plant mass at all for the light level you have installed.
Co2 and fert levels play a part in this because they provide the nutrients for the plants to become healthy, but you can still have a healthy tank without Co2 if you tune the light levels. This can be seen in MD fish tanks' videos where he doesn't run Co2, but he does generally raise the lights to at least 30cm above the water level along with dimming them if possible to get the correct light intensity for higher-powered fixtures.
The above is the hardware/additives for the tank to provide healthy plants. There's another aspect to healthy plants, and that's regular maintenance, like weekly water changes to keep the water clean.
When I start getting algae, I do 2x weekly water changes and might even go to 3x weekly water changes because something has caused an issue in the aquarium and the cleaner the tank is the better I find the plants can grow.