Free plants from a lake: hornwort, grass, and much more
The easiest way to get free aquarium plants is: go on a trip on the small lake and gather it from the water. It will grow fast even in low-tech aquarium with basic led light, no fertilizer or co2, just fish and water inside. Good thing is that adding plants to your aquarium makes it a heck of a lot of easier for you to maintain it. Aquatic plants helps you clean the water and fight with algae. Of course to the certain point and if you do it right and maintain proper ration of amount of fish and aquarium size. More developed plants have better access to all nutrients in the aquarium than algae, and are kind of strong competition to them. It also produces oxygen and uses co2 which is excreted by fish.
Your fish will be happier than ever before 🙂