Join Date: Jul 2010
Location: Outside Philadelphia, PA
Floating plants like you have can block a tremendous amount of light, so yes, I'd expect the carpeting plants to take a beating as far as light goes.
If you have a lot of floating plants, you may need a large amount of light id you want it to get to the bottom of the tank. I always found that you do need to remove a lot lot of floating plants from time to time, because they can easily get out of control.
Floating plants can help reduce algae, since they cut down on the light.