I have a 20 gallon tank and i am wanting to add some plants to it. i have gravel so it would need to be something that would be able to thrive on that. as of right now i have a nice piece of driftwood with some flame moss on it and a castle. im looking to get rid of the castle, center the driftwood and put some plants on the sides maybe towards the rear corners. i have some serpae and some painted tetras in the tank and i know they would definitely appreciate some more plants. any help would be greatly appreciated.