I have mentioned this before on this forum but as long as the discus start out good sized and the Geos of the peaceful types, they make a very interesting combination.
They are compatible, given adequate tank size and the discus often trail the sand sifting geos on the look out for bits of food the Geos stir up. Discus do a lot of sand sifting themselves when kept over sand substrates. I have some Heckels set up in a tank that has the back half terraced through the use of a glass planter box and the front half has only enough sand to barely conceal the underlying bare glass bottom. They will sift that front sand for as long as it takes to find every last live black worm. I always pot my Sword plant. It lets me redecorate easily and the pots confine the substrate fertilizer with the plants. I recommend potting plants in a Geophagus containing tank.
Here is their set up.
Overview of their tank. It is easy to see how the worms can't disappear completely into the sand and escape but the numerous craters the discus have made worm hunting are difficult to see..