I have an existing 30" long tank with a gravel substrate and no plants. Now I would like to grow some plants. Do you recommend adding laterite or something else rather than putting the plants right in the gravel? Can I grow certain plants right in the gravel? I would like to keep simple, low maintenance plants, so I do not need the "ideal" set up for a wide varierty of plants, but I'd like to do it right. Thanks.