i have had bad luck with API brand stuff and generally avoid them, but if multiple ppl can say this works i can give it a try as well, its just there medicines have failed me in the past and there test kits have been really bad, i got sick of there test kits and got hannah checkers witch did in fact prove how in accurate they was for me.
a example would be the nitrate test kit told me i had 60ppm nitrate, witch made no sense to me, so i had a lfs test my water and tell me diffrently and my hannah checker also says diffrently.
also have had fresh water tanks get ick a few times when i first got into the hobby, the api meds failed me and my fish did not survive, i have sense went to seachem, metroplex and garlicgaurd combo and it treats anything i have had to deal with so far.