Dear All Please help. One of my tanks is 250 Litres, and I have 6 zebra danios, 5 angels, 1 golden gourami, 2 bala sharks and 2 algae eaters. Its a well planted aquarium, however I am unable to keep the plants in the gravel, i have 4 inches thick gravel (really fine) and latex rocks and stuff, but no matter how deep I stick the plants in- the elodea and is out swimming in the water within a few days. after 1 year of this- I have decided to put terracotta planters- now the other plants are fine, but the Elodea is still OUT. I donot know what else to do. All the plants are growing well- and knock on wood- are healthy looking, but they wont stay in the gravel. any solutions would be appreicated. PS- I dont have this problem with my other fish and aquariums.