body fungus treatment

I'm hoping someone can advise me on the best treatment for body fungus. One of my rosy barbs has been battling it for a while now. She has little cottom tufts growing on her fins like white fur. It's most certainly fungus. I've recently found that all my other rosies are getting split fins with white edges. I treated with melafix for the last month. Every time I would stop, the fungus would come back. So I finally broke down and got some real meds. I chose API Fungus Cure. I didn't work. IT's been 6 days and there's no sign of improvement.

Has anyone had success with a particular brand? I don't want to just keep trying various meds, stressing the fish and blowing money. Any reccomendations? I did try to get a pic but the darn fish wouldn't stay still long enough for the picture to turn out.

Active ingredient: 3 mg Victoria Green B and 30 mg Acriflavine
55g with:

5 rosies
3 pepper cories
2 clown loaches (3" each)
2 chinese algea eaters (4" each)
3 banded khuli loaches
1 golden gourami

maintenance: 25-30% water changes weekly
filtration: Cascade 1000 canister

Water parameters

okay I have to confess the only test kits I have are ammonia and PH. I've never really had any problems that required me to get nitrates or nitrites. I know I should have a master test kit. nuff said. Anyhoo, I'm a bit surprised to see that right now my PH is 6.6. It's always run exactly 7.0 in the past. I don't know what kind of factor that is with fungus, but I think I'll add some PH UP. Ammonia is 0ppm.

Thanks for the reccomendation. Sounds like maybe I should put the rosies in my empty 20G and treat them there. The big tank is planted and no one else is showing any sign of being infected.

okay will do. I didn't realize there was anything wrong with it. Is there something that's better and more natural to increase my PH?

perfect... I have a whole bunch of whole oyster shells in my backyard. I'll just boil one up and crush it. Thanks!