I asked this on another forum and got no answer, so hopefully you all
will have an idea:

Background:
On Friday the 4th, I set up a 6g aquarium with Flourite (lots of it)
and some plants. On Saturday the 5th, I added a betta and on Monday the
7th, I added Bio-Spira. Some snails came with the plants and I've been
removing them when found (I don't really like snails) - there haven't
been many - maybe 8 found. We are very careful about not overfeeding
the betta.

I don't know what the plants are as they weren't labeled and the clerk
didn't know - but I liked them, so I thought I'd gamble. They seemed to
be doing OK until Saturday morning - one of them has brown spots on it,
but it does NOT look like sunken spots like you see on diseased or
mal-nourished plants - it's raised up from the leaf like something
resting on it - perhaps algae or something? It's kinda like dust and
comes off easily - even the betta swimming between the leaves knocks it
off.

Pics are he

overview (339KB): http://www.lizmcguireonline.com/overview.jpg

closeup (30KB): http://www.lizmcguireonline.com/closeup.jpg

....can anyone tell me what it is and how I get rid of it (if I should)?
Also, if you happen to recognize the plant, I'd appreciate knowing
what it is.

Tank specs:
6g (US)
pH 7.2
temp: 80F
8W florescent light
3-5 inches of flourite (depending on where in the tank) (so I'm
thinking only 4 gallons of water).
ammonia and nitrite: 0
nitrate: 15

Thanks,

Liz