I'm going thruogh the same thing you are right now. I removed all my fish from the main tank and put them in a HT when i noticed ick. I wouldn't use the RX-P in the main tank or the HT, that stuff will not rid you fish or your tank of ick. The ick in your main tank will be gone in 23-30 days with no host(fish) in the tank. If i were you i would treat the HT with hyposalinity, i'm doing the same thing. Just bring your salinity level down to 1.009 over a two day peroid and leave it there for four weeks. Than slowly bring levels back up to normal levels. Remember to make regular water changes so your HT won't cycle. Don't be nervous about doing this, at first i was but the prosess is easy and fish really don't seem to be stressed or anything. Almost forgot, make sure that your hydometer is accurate to make sure you are at 1.009. Hope this helps you out. Good luck.