What about plant food (like liquid plant food)? Wouldn't products like the Flourish line be benefishal to the plants?
btw, I have anacharis in my 10g with 15W 9350k lighting, and it isn't growing at all. I just got Flourish (a comprohensive supplement for the planted tank, or something like that, there are multiple Flourish products) and I am hopeing that will help the anacharis grow. My Hornwort is takeing over the tank. But so are diatoms.

(sorry for changeing the subject, I am pretty new to planted tanks.)