Here have a look at this website.
I use canna classic which can be used on all hydro or soil mediums.
Then at the bottom of the page there is a list of all their additives.
In the website you will find a "grow guide" which you can fill in and it will tell you what additives you need to use and when.
Its only a guide so you could use half of what they recommend with good results.
http://www.canna.com.au/products
Goodluck with your grow. Its a hobby that when you get started its hard to stop.
I dare say it's more fun and addictive growing than smoking the stuff.
There is plenty of good infor here on riu and plenty of people to lend a helping hand.