I don't know about gravel, but I've done some nice lush tanks with sand. First one without any kind of ferts in the sand, but there was alot of mulm built up in it. It took a long time to get going. Second I put ozmocote tabs under the heavy root-feeders like the anubias and crypts and they seemed to love it.
When I can no more stir my soul to move, and life is but the ashes of a fire
When I can but remember that my heart once used to live and love, long and aspire
Oh, be thou then the first, the one thou art, be thou the calling, before all answering love
And in me wake hope, fear, boundless desire.