Ive got alternanthera reineckil growing out the top of my 24 inch tall tank . It iseems to be fine with doing so the stalks have thickened up which is a plus and more plants are now starting at the bottom. Do i need to trim and replant the tops in the substrate? i just leave the glass lid open under my my ten inch tall wood canopy , but my lights are only 7 inchs above the water (yeh i know they need to be closer but i have my reasons hehe).