I'm in the beginning stages of a major rescape in my 46g bowfront. For a long time now, I've had a forground of e. tenellus red/micro. As part of the rescape, I'm planning to pull it out and go with dwarf hairgrass. People tend to use both eleocharis acicularis and eleocharis parvula as foreground plants, and both are referred to as "dwarf hairgrass".
What are the differences between the two? I'm looking for the shortest that grows the fullest.