The 5 days is correct for flukes and 30 days for most strains of ich. I've successfully used hypo for prazi resistant flukes and it worked very well when I couldn't get fenbendazole quickly, the part that you need to be careful about is if there's another parasite like velvet that you need copper to treat. Hypo can suppress velvet, brook, and uronema and you may not know you have it until you start to bring the fish out which has to be done slowly. Hypo makes copper very toxic, per humble, chelated copper is only safe at or above 1.017 sg and ionic copper is only safe at a normal salinity of at least 1.022 sg