I have no real experience with Pygmy chain sword except when it died in my tank before I started using CO2. This one will need CO2, grows relatively fast and spreads by runners. Best to plant them with some space between each plant (3-4 inches). Another important point is to plant them a half inch to an inch away from the glass, runners reach the glass pretty quickly. One every four inches in a tank that's 24 by 12, add a few for good luck = two dozen.
Echinodorus tenellus, which, unfortunately, is being renamed to Helanthium tenellum, grows like the weed it is with reasonable light and a rich substrate.
Its height is very dependent on the conditions in which is is grown. I have it in most of my tanks, and it's height ranges from an inch or two to about 10 inches. If you want to use it as a carpet, be sure it isn't crowded and has enough light or it will become a background plant.
Its runners also have to be pruned because under good conditions it will spread rapidly to places where you don't want it.
dbazuin;56981 said:It is a bit high for a carpet I think. It grows 5 inch tall easy. Further don't keep it to dense becouse it stops the flow go trough it and then it get algae.
Beside that it grows like weed in a CO2 thank never tried it on a non CO2 tank. But my guess is it does grows very well on exel.
http://www.tropica.com/advising/plant-articles/pogostemon-helferi-.aspxPogostemon helferi is a different but beautiful foreground plant which under good growth conditions forms a dense carpet of dark green leaves. The curly leaves and different leaf form make it stand out from the crowd of other foreground plants and thereby, it creates an attractive variation and regeneration of the planted aquarium - Tropica
Tug;57015 said:If you are still considering plants, this might be an option.