The question is what kind of substrate do you have in the tank now. If you had discus you may have put sand in there.
It seems to me all you have to do is do a new aquascape by taking out the high light plants and put in low light
plants. Crypts, ferns, anubias, and I think even swords will work. Then downsize with your lighting. There are
numerous threads on proper substrate for low light and discus.
Jeff