Adam, great info. Thanks! I've gotta LOL on all the dosage differences "from the source" that I've got. I called back the Doc...also inquired with Thomas Labs, who makes Quine Forte (I suggested to Jaime earlier)...incidentally who also gets their raws from the Doc...so I got 2 different answers from Doc (first - 5-7 grams per tsp, second - half that)...then Thomas Labs tells me 12 grams per tsp...emailed with they guy I bought my supply from on ebay who (like you) used a scale and he tells me about what you said (3.2G/tsp) so that's pretty close to your measure... My company sources raw food powders for products so I know somewhat that measures can change depending on humidity, density, powder structure etc so maybe some of that is at play.
Anyway...here's what I'm doing for my 200 gallon tank...since for now I only see mild display tank Ich issues: 1/2 tsp at AM, repeat at PM, no carbon or skimming, lights off, normal water change schedule (about 10-20% once weekly). Will try that for 3 weeks. This is more of a prophylactic dose but we'll see what happens.
Fishman says the half life is 12 hours, and that light affects the stability versus life, so I figure this dosage method far superior to the conventional method of a large single dose once every week...and hey, if it has worked for 10+ years for the big outfist (Bass Pro Shops etc) then its worth a trial run for me...
Jaime mentioned the other quinine drug to me as well - I will try that next (if this doesn't work). It is possible that the Harlequin Tusk that I had go blind was due to quinine sulfate (during my last Ich tank wipeout last year - which I thought was kicked by a fallow tank run - and why I'm cautious with current fish population in seeing that it did not fully die off in my tank).
(By the way Adam, have you put pics of your FOWLR up anywhere, would be great to see).