I had velvet go though my tanks and it is one of the worst things to see your fish die from, it really puts them through hell before killing them
I never shut off the lights and I didn't raise the temp, just took all the fish out of the display and QT'd them in a seperate tank and treated them with cuppermine (or however you spell it
). I kept the fish out of the display tank for 8 weeks before putting them back in.
Here's a link to my marine velvet thread, there is a lot of good info in the links I added to that thread and there is also some very disturbing pic.'s of what the velvet did to my fish.
http://www.canreef.com/vbulletin/sho...t+horribleness