If you are going hydro try Vita Grow products they work equally as well in rockwool / promix / hydroton. If you are going soil inorganic then you can try peter's it's a powder you mix with water it does not build up as much in the soil as say your Miracle Grow (but even with Peter's you still need to flush every so often). Soil organic would be bat guano, budswella, fish emulsion ect. The Vita Grow is probably one of the best going though.

Herbus