Algae is a hard thing for most of us as it does come in so many ways. There are very few who do not have some algae but the main idea is to keep it from becoming such a problem that it grows on plants and keeps them from getting the light they need to grow.
Sounds like you do have enough light for the plants, keep watch and try not to give the tank too much light as that can make algae grow very well. But for the plants, they also need some form of carbon to grow as well as some form of food. The carbon can be from CO2 or it can also be from liquid like Excel which is a liquid form of carbon. Also the plants will need some form of food. We often call it fertilizer or ferts. Some of this food can comes from the waste from fish and fish food but that is often hard to control and we often find we need to add ferts in some form to get better growing plants. The better growing helps to use up some of the nitrate and keep the algae from growing so well.
So we often speak of a "balance" of light, carbon (CO2?) and ferts. Getting this balance, while watching that algae doesn't get out of control is something that most of us never really get totally under control as it can sneak up at any time.
Like having a cold or the flu? It is always ther, waiting but we need to try to control it. In tanks that do not have plants, we often just scrape the algae off the tank walls but when we want to grow plants, we don't want to try to scrape it off them!