Thanks Mike, I hope you're right. I have had him a little over a year and did not seem to have ich in my tank until a month ago when I added a rusty angel, I did QT the angel but she looked healthy in QT so I didn't treat her, she still looks healthy, not a spot of ich on her but soon after adding her to the DT the scratching began.
I bought him locally from a store called the box of water, he did have his adult orange spot when I bought him but was smaller, he has grown in the time I've had him. He was the first fish in my tank after letting it sit fallow for over 3 months, he had the tank to himself for a couple of months and learned to eat, when he started eating well I added the other tangs and 2 angels all at once from my old tank, all was great until the addition of rusty.
Most other creatures need the right conditions to breed, I would think ich would be no different. Anyway for whatever reason lights out has helped alot. Recty with that info I guess the best time to vacuum and water change would be at night.
Pran, my temp is 80, not sure if its high enough I think they usually recommend 82, correct me if I'm wrong.