I'm creating a self sustaining aquarium. Well, have been for about 7 months now. The tank is roughly 20 Gallons, I have a ~2 in level of sand/kitty litter, with a ~1 1/2 in level of Pea gravel on top of it. I have Amazon Grass planted, Java Moss, and what I can only think is Anubis planted in it. I have a colony of Ramshorn snails in the aquarium, and a small colony of Guppies. The **** is building up, and I fear that the nutrients are not being cycled through the aquarium. What I want to do is plant a carpeting plant that will survive and grow in Pea Gravel. I have already tried dwarf grass, and it died. If anyone can help, I would appreciate that.