puffer

So I am new to corals and only have one at the moment, a zoanthid. I am only using the stock LED lights that came with my aquarium kit so I was not going to introduce any corals until upgrading my lighting system at all, but it seems I gave in to try out one that was known for not needing much...

So I have a porcupine puffer that I just got a couple days ago, he now has ich. I have 8 assorted damnsels, maroon clown, coral beauty, yellow wrasse, and a yellow goby in the tank with him. Could I just use hypo on the whole display tank to treat the ich? If so, should I lower it all in one...