I keep live plants in my tank, and I think it helps with water quality. You may or may not be able to keep live plants in there, it all depends on how the eels take to them - mine always seem to dig up one particular plant. I have a piece of driftwood in the tank, and have some sort of aquatic plant growing on the top of it - the roots are in the water, and about half of the plant is out of the water. I also have some java fern and a sword plant.

Don't plants give off oxygen, not carbon dioxide?

Katrina