columnaris treatment?

I have a flowerhorn that i believe has columnaris. She got a little beat up one day so i removed the culprit from the tank hoping that she would get better once the stressor was gone. She ended up getting worse and was very reclusive and not feeding. Added some salt and copper sulfate to tank b/c i read that both can help and i had both on hand. Seems to be doing better and eating again however her tail and dorsal condition still concern me. Want to hopefully have her recover fully. ammonia 0, nitrite 0, nitrate 20, ph 6.8, temp 81.

I have read so much conflicting info online. So my question is if anyone else has experience treating it what worked best?

Sorry forgot hardness above: total hardness 60. ammonia 0, nitrite 0, nitrate 20, ph 6.8, temp 81. There was a Aulonocara jacobfreibergi, blueberry zebra, and a salvini all of which I removed. Believe the peacock and salvini were picking on the flowerhorn. Right now there are a few giant danios and 2 silver dollars as dithers, a yellow lab that my son is very attached to, another smaller female flowerhorn, 6" synodontis, and a pleco.

Thanks. The thing that got me a little worried was the dorsal and tail looked shredded a little and looked like white fungus on them. Already starting to look better in pic. I know that severe stress can lead to compromised immune system. Was also reading about columnaris presenting as fungal looking and can come out in times of stress. Was just trying to prevent it getting to point of no return. Guess I just got a little nervous. Will keep an eye on her.

Thanks again for your help. She does seem to be doing better and eating better.

Thanks. Already did the salt and going to do some extra wc this week.