I have a 20 gallon tank. with marineland 350 bio wheel filter , and a marineland single led lighting. i currently have sand in the bottom from top fin . Inside the tank i have 6 bleeding heart tetras,6 black skirted tetras, 3 mollies,6 skirted tetras , and to tiger snails at the top of it there is a breech with wood which has 2 red claw crabs. so as you can see i have a pretty active tank. i really didnt want to plant this one but over time i started thinking about planting it . would it be smart to plant the plants just in plain sand or should i have a bottom substrate of eco complete or flourite or can it just be sand ?