I used the levasole powder for my successful and well documented RED PLANARIA intank kill experiments.
I had found that you had to keep the mixture derived from the powder in much less concentrations than 5 grams per 300 gallons. And a couple folks that did not follow my directions on my planaria thread had near COMPLETE losses.
My SPS tests with my levasole powder mixed at 1/2 teaspoon in 240 ml water was that at a rate ABOVE 5ml per gallon of system water that SPS and plating monties died in a DIFFERENT parasite in-tank eradication test. You would see instant oozing and tissue degrade on some and all would be pale dead sloughed sticks by the next day. This was testing that I did against montipora eating nudis, but the concentration and my dosage is the main point I'm mentioning.
My point is that I suspect that the boulus/tablets have quite a bit of filler in them. Also, there are about 4 or 5 companies that produce "Levamisole Hydrochloride" and the key to any of them is making sure you are aware of concentrations of "active ingredient". I suspect that if you took 5 grams of "drench" and put it in a 300 gallon system you'd see very dismal results due to concentration of the powder.
Either way, good luck on your trial.