Personally the only thing I'd recommend is kordon Formalin III. 1mL/gallon in a bare bottom quarrantine tank with a heater and an airstone. Use Amquel to neutralize ammonia before it starts. Dips are too harsh IMO and usually just finish the fish off. Some say use a warm tank to speed up the life cycle of the disease. Unfortunately it also speeds up the metabolism of the fish. If the fish can't breathe already it will only make the fish more out of breath and more likely to perish. So, I prefer to lower the temp to somewhere around 75 degrees. Once the fish starts to recover, you can start thinking about things like speeding up the paracite's life cycle with higher temps.
Hyposalinity is also helpful when used in conjunction with Formalin. as i understand it it also allows for higher levels of oxygen in the water. Given that brook and ick are usually colonized on the gills first, I'd say this is a good thing.
Whatever you decide to do, do it with a quickness. If you're fish already has the film and is gasping for air at the surface, I would suspect you don't have much time to waste.
Your fish could also have amyloodinium. Which, I would treat the same way. the problem is that it is harder to erradicate from the main system. Either disease can infect other fish without visible symptoms. So, your clown could easily get it again once you add it back to the same old system with it's old tank mates.