I feel like anacharis can pretty much be grown anywhere as it is close to a weed, well, at least it grows like one haha. I dose anyway just because I like to encourage healthy growth but either way I feel it should be fine. I would even get a desk lamp for the tank though to make sure it got a sufficient amount of light a day.
In fact, I'm more worried about the sword, they need a little more lighting than anacharis does as it grows in all conditions. I would definitely look into the root tabs though, any plants that are rooted in the gravel will also benefit from them, however not sure if you floated the anacharis if it will also reap the benefits just from being in the water. So this way you'd just be getting the tabs and not a liquid fert or anything.
RJ (H. Lifalili), Acara (EB)
Ghost, Tuxedo, Trip (Angels)
Leopards: 1:3 Hawkeye, Luna, Astrael, Dorian