Originally Posted by
jeep
HITH can be caused by several different reasons - water, diet, environment, filtration, hex, etc...
Your water change schedule seems sufficiently good. Nitrates excellent! You feed a varied diet but do you add vitamins and minerals to the BH? Do you know the KH of your water? The TDS? A lack of minerals can contribute to HITH. What kind of filtration? Carbon is believed to be a cause as well.
Hexamita is not really considered to be the cause of HITH but rather an effect. Hex is opportunistic and can infect an existing problem. Is this affecting one fish or several? If only one then it would be much easier to treat in a smaller hospital tank.
I would keep up with your water change routine, add 1-2 TBS salt per 10 gallons, feed a varied diet with a solid vitamin and mineral content, raise the temp to 90 and remove any carbon in the filtration if present. If you want to treat for hex again, treatment for hex is best at 93 degrees with metro.