When most people here floating plants, it brings back memories of heroic battle againsts duckweed but many floating plants can create a beautiful addition to your planted tank. They help to provide shaded areas on your tank floor where you can grow plants that do not require as high of light, they help to draw out extra nutrients in the water column and provide a safe haven for fry.
Many floating plants are very easy to grow and prefer slow moving water. Tanks with large surface agitation will inevitably kill your floating plants. Floating plants will end up finding a calmer spot in your tank to grow but it will take some time for them to start growing