I am planning to grow plants that need a acid substrate and I have eco complete substrate, 2 inches. I am also planning to do a rescape so I can have 3in of substrate and plant rearrangements, so that means I'll can add peat moss on the last bottom layer of my substrate? from above will be eco-complete...say would 20lbs of peat moss will suffice? Or is that way too much? 10lbs of peat then? A link to where to buy this peat will be greatly appreciated.