5 days, is not a long enough time to cure ick.
The only way to cure it, is for all cysts to go thru their life cycle, and the vulnerable stages to become killed by the salt, and/or meds.
Since you cannot raise the temp, the cycle may take weeks to have all protozoa hatch and become vulnerable. The type of meds do not change the times line.
If a parasite hatches into the tank, and the osmotic pressure of the salinity or the med is strong enough, the cell will die, if not it will reinfect the fish, the the cycle begins anew,
Salinity must be at least 3ppt (parts per thousand) 10 lbs of salt in a 325gal, or the ick not implode, it will shrug it off, and reinfect the nearest fish.
And just because a fish does not have obvious outward symptoms, does not mean its not infected, if ick is in the tank, you must assume all fish are infected.
The only way to cure it, is for all cysts to go thru their life cycle, and the vulnerable stages to become killed by the salt, and/or meds.
Since you cannot raise the temp, the cycle may take weeks to have all protozoa hatch and become vulnerable. The type of meds do not change the times line.
If a parasite hatches into the tank, and the osmotic pressure of the salinity or the med is strong enough, the cell will die, if not it will reinfect the fish, the the cycle begins anew,
Salinity must be at least 3ppt (parts per thousand) 10 lbs of salt in a 325gal, or the ick not implode, it will shrug it off, and reinfect the nearest fish.
And just because a fish does not have obvious outward symptoms, does not mean its not infected, if ick is in the tank, you must assume all fish are infected.