I picked this stuff up the other day for my 6 gallon. Can you use it alone or is it recommended to put regular sand on top of it? This is what it is in case you don't know (http://www.sera.de/index.php?id=301&L=1
), as I had never seen it before. I will be ordering my plants either today or monday. I have some of it floating on the surface, but just a little bit the rest has seemed to settle down.