Originally Posted by RussellTheShihTzu
If my plants were doing well without anything I'd let it alone. "If it ain't broke; don't fix it," as they say.
However, Crossroads is right, most recommend Seachem Flourish Comprehensive which is what I use. Others recommend Seachem Excel but I caution to dose it half and build to a full dose as I've had it melt/kill plants. Excel is not a fertilizer but a liquid carbon source. Lots of people have good plant growth with it.
I try not to dose anything unless my plants tell me they need something. They'll show signs of a particular deficiency, which makes it a simple matter of knowing what to dose.
I've come to realize that with plants, it is as important to learn about my water as it is to choose plants or fish for particular set of conditions. All I mean by that is though experience, I know that with the way I prep my water, it is deficient in Fe, K and trace minerals. So every planted tank I have, I know I need to dose these as a bare minimum for healthy plants. If anything more needs to be dosed, my plants will tell me what that might be.
Having said that, I am reading about a different dosing method. It's new to me so I won't confuse the issue here. I know that what I have outlined above works well.
EDIT: I should mention that this is most effective with water column feeders. Rooted plants are a different animal and generally rely on what substrate and root tab configuration I use. For me, I have learned that Flourite combined with SC root tabs works very well with my Crypts.