I am looking to plant some plants in my tank. I currently have blue gravel in my 55gal tank. I know to buy good substrate and don't necessarily need sand. Do I need to take out much water to make this change over or can I just try my hardest to get out the blue gravel first, then slowly put in the substrate? Am I confusing anyone? Sorry if I am...I am kinda new to the plant thing and really want to have them instead of the fake ones. I do have a couple real plants and two flora lights. But they don't seem to do too well. ANy help is muchly appreciated before I tackle this.