Empty wrote:

Other good choices include the various lilaeopsis and echinidorus
tenellus (narrow leaf chain sword).

A half dozen E. tennellus took about 3 months to completely cover the
bottom of my 10 gallon tank. Since then I've "harvested" double
handfuls every few months.

IOW, it's a great ground cover, but if it were a land based plant in my
garden I'd have to keep it in a sunken pot to keep it from replacing my
lawn :-).