Most do 2 x a week water change, 50%.
Many people feed their discus a lot of food.
This turns into NH4 waste.
NH4 is a causative agent for algae.
I typically keep adult fish at about 82-84F.
Use less rather than more lighting, 2 watts per gallon is a good range if you use powercompact lighting.
I generally suggest dosing 2x a week after the water changes and good feedings.
Some hobbyists add traces such as Tropica master grow each day as well.
That's a good routine and set up for Discus.
For young or fry, lots of water changes and food+ bare tanks, once they are adults, then you add them to the tanks etc.
Some folks do not mind slightly stunted adulted. My fish where still about 5.5- 6" so instead of say 7-8". I could have fed more and done more water changes etc.
I do not like them Bigger anyway for the planted tank, it'd be nice if they all stayed 3-4" to tell the truth.