Hi,

I assume you mean an open top water barell. I have extra anacharis from my fish tank in mine and some of the stuff folks call "pond scum" - its the tiny floating plant with little hanging roots and it reproduces really fast - frogbit maybe. If you go to your local fish store (petsmart will have it) you can get anacharis cheaply and probably some "pond scum" too if you look around in their plant tank. It often comes as a hanger on with aquatic plant shipments. I also have riccia which is another floating aquarium plant that grows like crazy. The water stays nice and clear.

I also have mosquito fish in there which I have found to be essential. If you are looking for something prettier I am not sure what to suggest.

HTH,

Kate