Hi Tom, I notice over time that I succumb at times to not dosing EI as reqularly as needed and I do not have a good person for when I go away for extended times.... The plants will do better with extra sources I am sure. So, I have black flourite now (< 1 yr old) and would like to have some substrate nutrients available to my plants as well. Can I add worm castings or such UNDER the flourite? I can do sections at a time to facilitate things and reduce risk. The tank will remain filled (well partially anyway) during the swap as I do not want to tear down the tank completely if possible Or is it better to bite the bullet and replace with a 'better' nutrient rich substrate and still do a section at a time. I dread the thought of adding ADA to a mature tank due to NH4 leaching.......... It is a mature 180 gal tank with good mech and bio filtration. Many cards and not much else but some Espei pencils. Any suggestions are welcome.