Funny, I was going to post a thread on this too. I've heard that some use 72 watts on their 10 gallons, but I have DIY CO2 and can only imagine what would happen should I forget to replace the sugar/yeast for only one day.
Myself, I'm running the coralife 28W fixture. The blyxa doesn't seem to do well at all with the lighting, but everything else does OK. I think a lot of people have success doing the retrofit 36W from AH Supply.
By the way, does anyone know if there are any T5 bulbs I can fit into my 28W coralife fixture? It's 20" long, and from what I understand any bulbs should work fine, but they'll be overdriven?