I want to get some moss for my 20 gallon long tank. I'm not into tying moss on rocks. I like the idea of just a big ball of bright green moss growing somewhere in the background, like this: My tank has 74-76 degrees water and medium lighting. I don't use co2 or any other plant additives other than the occasional Seachem Root Tabs. There are already 8-9 very established plants in the tank like vals and amazon swords. Between Java, Christmas, and Willow, What kind is most likely to achieve that brilliant bright green seen in the picture above (with my water/lighting condition, and floating instead of being attached).Which one grows the fastest?Where's the best place to buy them (they are all so expensive!) Thanks!