I recently started a planted tank (25G). I added CO2.

I've been mostly lurking here and notice there's plenty of discussion on
additives for the plants. So far I'm just using chelated iron. I noticed it
is being used up everyday.

1) Is there ONE supplement which I can use which includes most of what the
plants needs?

2) Also, I am kind of mad at myself for not researching enough on the
gravel. From what I read I should have used Flourite. I'm thinking of
replacing the gravel with it it, or at least mixing some in.

What do you think?

Thanks!