Yellow Tang with Black Spot disease

[TANGOMAN]

I purchased a Yellow Tang 4 days ago and noticed today a "mild peppering" of black spots. The fish began occasionally scratching two days ago so I've been expecting some parasite to come a knockin'...
I've never seen this before and reading "Natural Reef Aquariums", Tullock refers to this as an "external worm parasite". "easily treatable..." (easy for him to say ). The fish is, and has been in quarantine so capture/treatment won't be difficult. It's the form of treatment and success that concerns me.
Tullock recomends "a dip in a bucket of seawater containing a solution of PICRIC ACID..."
Sounds too good to be true...any experience with this is urgently/gratefuly appreciated ! What's the availability of this product in Calgary?