Oh. Well, do you have enough circulation in your tank? If you have enough plants, they will handle the bioload. Your filter then becomes a device for mechanical removal of particulates and chemical filtration if you want it. It will still provide a home for beneficial bacteria, but it becomes less critical if your plants are growing. You might not really need to change anything.
The sump can definitely be used, especially if you don't go the CO2 route. More water never hurts.