OK, let me start by saying I am not a big advocate for dumping in chemicals into my reef to resolve issues like Ich, hair algae, etc.
With that being said, I have just won a battle that I have been fighting for the past four months. I picked up some corals from a guy that was breaking down his tank and there were some flatworms that hitch-hiked for the ride. Within a month, my 75G tank was crawling with them. I tried siphoning, but it was a losing battle and fresh water rinses were impractical as I have 90 lbs. of LR. Many of the pieces wouldn't fit in a 5 gal. bucket.
I was very reluctant to use Greenex, but it was impossible to enjoy my tank! I would have to look through the front pane of glass that was covered with tens-of-thousands of FWs! The rocks were crawling with them. I even noticed that my yellow polyps and green mushrooms would detract whenever they made contact with the evil beasts!
I followed Righty's directions and had a large tupperware container filled with fresh salt water at the ready expecting the worst.
At first, I was disappointed because the worms didn't really convulse or writhe as descirbed by Righty

but at the same time neither were my snails and the polyps on all of my corals never flinched. After 4.5 hours, I turned on the pumps and the water column was filled with lifeless FWs. I let my carbon laden Magnum run overnight. When I woke up the next morning, almost all of the FWs had been eradicated. ...WITHOUT A SINGLE LOSS TO THE GOOD GUYS!!! Even the pods seemed relieved to be able to run around on the live rock now that the un-invited guests had been ousted!
Now I did say that
ALMOST all of the FWs were gone. I followed up later that afternoon with another treatment, this time only a 25% dose for three hours. It's been three days now and I haven't seen a single rouge FW sliming around.
My hats off to DMM32 and Righty

for having the guts to try something like this in the first place! And Righty, thanks for writing the procedure down in such detail. I am convinced that the method of delivery was key to it's effectiveness.
-E!