>>The worst thing happens when your Riccia starts to mutate (see the similarities?) Some of the Riccia will turn a horrible dark green. This kind of Riccia will not float. Neither will it bubble. It will just look ugly.<< I have been growing Riccia for 5 years and never seen this happen. Maybe you got a little java moss mixed up with your Riccia! Robert Paul H http://www.aquabotanic.com