i want to start a 75 gal planted tank i was wondering wat type of substrate i should use. im going to start with easy plants and a nice ground cover like dwarf hair grass
Discus are probably not a good fish to "learn" with, especially in the planted hobby where you are adding co2, nitrate, phosphate, and other things that are toxic to fishes.
That being said, I use and like eco-complete with my planted tank.
Use a 2-3in bed of flourite. Plan your lighting out carefully too. Dwarf hair grass will need pretty bright lighting, but if it's too bright, you'll need to inject co2 to prevent algae.