Hypo-Salinity in QT
 

So even after about 2 weeks of QT, my Purple Tang has Ich. It was doing great after 2 weeks up until I caught the Yellow Coris, Mystery Wrasse, and my Randall's Anthias and quarantined them all together.

The Purple Tang was covered in Ich as of last night, so this leads me to believe that Paraguard is great for prevention, but not curing Ich.

Hyposalinity here I come! I drained about 3/4 of the QT out, topped up with RO/DI and finally got Salinity down to 1.008.

As of this morning, majority of the Ich has disappeared from the Purple Tang. The other 3 fish show no signs of Ich nor stress from the Osmotic Shock Treatment.

The plan is to Hypo treat for 6 weeks, and then monitor for an additional 4 weeks.

Are there any tips for Hypo? I have 2 small filters going with just Filter Floss, about 10 lbs of LR, an airstone to help aerate the water, and a small powerhead to circulate water.

I'm feeding with NLS Thera+ pellets, a couple strips of SeaVeggies, and half a cube of either Mysis or Spirulina Enriched Brine. I feed the pellets during the day and the frozen at night. I'm planning to do about 25% water changes every 2 days to export nutrients.

Is there anything that I'm missing or that I should be aware of?

That's because you introduced new parasites by introducing the other fish.

Ich has to go through its cycle and Paraguard must be redosed each day.

It's best to keep hypo at 1.009.

Even with hyposalinity you will see ich get through its cycle.

That was the same conclusion that I came to as well, however I thought that the Paraguard would have prevented the Purple Tang from contracting the Ich.

I have been dosing Paraguard daily for the past 2 weeks prior to the introduction of the newly caught fish.

Would 6 weeks of Hypo be enough? Or should I go 8 weeks?

It depends. If you introduced the other fish while the concentration of Paraguard was a bit low due to time spent in the tank, then probably some parasites made their way to the fish skin.

Remember that a quarantine tank is not so big so the fish are very confined and the parasites can find them easily and fast.

If you had put them all together with Paraguard, I might have been a different story.

Did you dose Paraguard right away when adding those fish?