What type of grasses are there available? I'm on the look out for some Blyxa as it's about the only one I know, are there any that give a good coverage but stay short/grow slowly? I'd prefer something that grows outwardly quicker than upwardly, but that would not overtake my other plants, is that possible? I want to mix it in with the HC which I have just put in my tank (although I'm now not sure it is HC as the LFS said :? ) to make a nice carpet.