I have a 100g community tank with an assortment of fish, I was wondering if I could "spot substrate". What I mean is could I relocate a certain area of gravel and siphon in "planted tank substrate". This will create, in essence, spots of mineral rich substrate. I want to have some plants that flourish without having to remove all my gravel. The beneficial bacteria,etc. will go with it and I dont want to be loosing fish. I was just wondering if this is a good idea or not. Let me know!