The only solution it seems is to change water very regularly.
Many people keep discus with plants.
It's really like any other tank, except that the plants have to be able to handle the warmer temperatures you keep them at. This way, the plants will outcompete the algae for nutrients and the water changes will be kept low enough to prevent the build-up of excess nutrients. Make sure to choose plants that will withstand the high temperatures your tank is at. Look at one of the 'Nature Aquarium' books, they have examples of planted aquaria for Discus. Hope this helps.