Yea you can do a fish less cycle with plants, isnt going to hinder or hurt anything, the plants are going to absorb some of the waste your going to produce, but in the big picture wont matter all that much.
If your serious about having a planted tank i would invest in some proper substrate such as Red sea florabase, Flourite, or many people use Eco-Complete, there is also AdA substrate out there. It all really depends what your taste is, they all have different looks and different uses.
The benefit of that stuff over sand or gravel is that gravel and sand have no benefical nutrients for plants. So if you have a heavily planted tank, most plants get all there nutrients from there roots, and the good expensive substrate you bought does just that job. Sure you gotta other stuff too but you got a huge head start over someone who is just using gravel or sand which has no nutrients at all. If you choose to go with gravel root tabs are usually a good thing, you place them under the plants and they provide nutrients that way.
Myself i love the look of my red sea florabase and it works amazingly, would never go back to gravel.
Tried sand in the past looks nice.. but a ***** to clean the tank... and can get very mucky.
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