sick fish not improving

[Escher]

Second attempt at posting.
My discus have had a problem with ick for over a week. Just when I thought they were improving, they are not!
This is the set up: 7 small discus (up to 8cm), one medium and two adults. 4 ft standard tank, 5.8-6.0 pH, 31 c temp; no nitrite, nitrate or ammonia problems. Planted tank.
I have raised the temp to 31 deg c (from 28), used praziq tab 10 days ago (2 tabs in black worms for 25 min) and repeated one day later mixed with food. Repeated treatment in water a week later. Reintroduced the charcoal in filter two days ago. Daily changes at 15%. Salt added at recommended dose ( 1 scoop per 40 L) - pH droped to 5.8 as I reintroduced the charcoal.
Some fish are still dark, flashing and one still with some white coating.
Any suggestion on how to get rid of the problem???
Thanks

[kevkoi]

U may be having a problem with hexamita which is what is causing the fish to darken... Course of action if hex is suspected is metrinidazole, but in a planted tank it can get tricky to medicate.

Do you have a separate quarantine tank?

[Escher]

I am quite happy to sacrifice the plants if necessary. I have a 7x2x2 tank curing and the fish will soon be moved - I am seriously considering making a bare tank, so the plant anda gravel might go from the current tank if this is necessary.
What are the other symptoms of Hex? My fish some are darker, some try to scrape their bodies, some stand in odd positions (not sure if it is bullying), some have a white coating.
At least they have not lost their appetite.
Thanks

[Proteus]

I would get some Metro ASAP, as Hex can get nasty, and nasty very quickly...

[kevkoi]

ouch.. now this sounds like velvet. Geez, which one is it now? Maybe you should drop by at SLS and if possible bring a digital pic of the fish (video would be better).... Hopefully we can knock it on the head FAST.

[Escher]

Murphy's Law? Hopefully yes! The store I could stop at did not have/know about Metro. I assume it is short for...
So I did nothing except observing. specially because after so many water changes, medications, and other things a gave it a rest; I just added some Geoliquid and now the fish look a lot better (coincidence? or less stress and better water conditions?). My medium Marlboro still has a whitish haze, but is not as intense as before.
Thanks
Gianluca

[weird]

Go to a doctor or vet, or under the counter perhaps at your local LFS.

It is called metronidazole, but commonly sold as Flagyl. I would dose 200 mg, for every 20/25 litres of water. Treat 3 days, and 50% water changes daily (make sure you keep your water temp constant). Proportionally readd metro with your water change.

Also I would treat with salt, I think 1 tablespoon per gallon (approx 40 litres). Make sure you use aquarium salt.

Good luck.