I am lucky only to have had 1 case of Ick in my 25 years, but it was about 8 ish months ago. No idea where it came from as I am very careful, but it got it. One of my darwins got it immediately and died within 7 days.
So I did a lot of research and came across thus Hypo thing.
The theory of Hypo is the parasite needs salt water to survive and if placed into a more fresh water mix, they would keep consuming water until they explode, thus killing the parasite. Kinda like a fresh water dip, but for Ick.
To be quite honest I just followed the prescribed reduction to 1.009, kept the water fresh with 1.009 replacement of 10% per day and in 7 days the spots were gone. I went another 7 with half strength cupramine, then 7 more days bringing the salt ppt up .002 per day until back to 1.026 where we started.
Saved a clown, a gramma, and a lawnmower which are back in the DT for about 7 months now.
I did not find it that hard at all, once I found the measure that made 1.009 water, it seemed quite easy. I nit iced the fish started eating again around day 4, then missed a day a few times, but by day 8 eating and swimming well.
It sometimes hard to say what is right...and what might be some luck.
Cupramine is the tried and true method which has been used forever. It kills the parasite and everything else as well, and if you use to much, the fish as well
Hypo, only seems to kill the parasite, and because the salt is so low, resipation is easier for the fish in this weakened state, thus less stress
I am assuming that I must have been close to 1.009, however not sure how close....could have been .008 to .010.....
Many using hypo use on tangs and delicates, whereas copper for the hardies....
I my readings, each person has their own opinion........