Browning/yellowing leaves on Epi x Encyclia cross
 

We won this Epidendrum floribundum x Encyclia linearfoloides at the NCOS orchid bingo a few weeks back. Prior to that, we kept mostly Paphs and Phals. Recently, it has begun to show brown spots surrounded by yellowing areas on some of its leaves, but we're not sure if it's viral, fungal, or our fault.

It's kept in our living room (fairly constant 78* F, ~45-50% RH), and we water it about once a week with tap water. It's about 18" below a dual-bulb T12 shop light with 6700k 40W bulbs; the other Paphs and Phals in this area look fine.

Here's a pic of the worst two leaves:
http://i380.photobucket.com/albums/o...G_0273_web.png

Any idea what might be wrong? Too much or too little light? Are we watering too much or too little?

Thanks in advance for any help or suggestions,
Chris

What kind of air circulation do you have?
Joann

Just the air circulation in our living room, so just what is driven by the air conditioning.