250 mg level should be good. I would not increase. You may need to change water twice in one day if it’s cloudy. DO NOT FEED IT, at least not for a while after treatment is complete. They can live for months with no food, eating only adds more posssibility if having problems. Feed it when it’s healthy, not while it’s adjusting to your care. Make sure it’s flow is high enough flow. During treatment, they need high flow, some may need extreme flow, to purge all the decay out of them to the point of recovery. They may not look good during this, but they must purge all the decay out, still water or low flow will not do this well.
Good luck.