the red plant looks like some kind of ludwigia @_@ but I really cant tell unless you take a closeup shot ^_^ <ignore this part, just reread forst post>
Which floating plant? :O
With your lighting, your plants may revert back to having green foliage.
I think you can improve on your scape if you don't scatter the plants aroud too much:D
and definitely arrange plants front to back according to height ^_^