I googled it and although I couldn't figure out what it is made of my guess is that it will be 100% ineffective. It appears to be for freshwater use, and in any case, most "medications" like that just plain don't work.
You can try a temperature matched freshwater dip to at least knock most of the cysts off, but IMHO, the only real treatments are, from least to most effective, Hyposalinity (difficult to manage and must be done it a QT, Copper (dosage strong enough to kill the Ich parasite can be very hard on fish as well, and once again must be done in a QT, and Tank Transfer Method (also need a couple tanks or even buckets with heaters and power heads)
If one fish on your system has Ich, THEY ALL HAVE IT and must be treated appropriately.