I fought the same battle and just read about this on Facebook and I registered on this forum just to answer your question.
The Coral RX works so does Bayer. For RX you need 20mL per 3.8L for 5 mins. For Bayer there is no standard regarding how much you put in but generally people go for about 5 to 10 mL per cup for 5 - 10 mins. More is not better. I got shocked reading that you did dipping for 3 hours. All you need for dipping is to knock AEFWs off and check the eggs. You do not need to kill them because that will seriously damage the coral in the same time which is why your corals have been dying.
I did dipping for 2 month, once every weekend, so eight times in total. If you use a QT you need to make sure the tank is cycled and is stable. Most importantly you need to make sure that the light is good for them (T5, MH, high-quality LEDs). I dipped non-smoothskin in RX, 10mins first time and then 5 mins since the 2nd time. For smoothskin I dipped in Bayer (RX tends to be quite harsh for some smooth skin corals) for about 5mL per cup.
I've been AEFW free ever since. After the first 2 dips I never found any more AEFW. But I had the same situation with you, my corals were dying fast and browning out horribly. Most of the corals survived the dipping actually fairly well. They didn't even seem to be quite bothered by RX/Bayer after a few weeks. PEs were great & colors got back after a month or so. You can use a small pump/powerhead while running the RX or Bayer. Long-time exposure in Bayer tends to burn off corals tips and their slime. Again, the goal is not to kill AEFWs but to knock them off. For RX I direct a small powerhead at infected corals and at round 2mins AEFWs fall off and usually no more AEFWs fall off at around 4mins into dipping. No you are not supposed to see large AWEFs falling off after several dipping. There must be something wrong with your previous dipping. You probably did not blow off all the AEFWs.
As for the fallow period, according to limited research people & I did recently, AEFW cannot survive more than 2 weeks in a tank with no AEFW. Their eggs hatch in a few days. AEFWs just hatched die without food in 48hrs. Therefore there is no point to wait for more than 3 weeks.
You really need to be patient and not to fall into that "more is better" / ''longer is better" logic. One dipping per week gives your corals more time to recover.
