Salt With Pleco / Corries

[San O Fisher]

So after a disease hit half of my discus in a matter of days I have them all separated in my QT Tank receiving salt treatment.  I would like to get them back in my regular tank, but I wanted to see how much, if any, of salt I could add to the tank.
 
It is a 92 Gallon corner tank?
 - 15 rummy nose
 - 15 Cardinal
 - 10 Schwartz Cory
 - 1 snowball pleco (who is growing very fast!)
 
3 discus to come back sooner than later.
 
How much salt could I add for a few days before I did a water change so the discus could adjust better?

 

[RainboWBacoN420]

Don't use salt. Your corys and pleco scaleless fish, and they will be super sensitive to salt treatments.
Also, corys shouldn't be housed with discus. Both have pretty much the same requirements in terms of pH and hardness, however when it comes to temperature needs, this is where they part ways. Discus need high temperatures, typically anywhere from 84°F to 86°F. Corys like cooler temperatures, typically 72°F to 76°F, depending on the species of course. The Schwartz Cory favors 74°F to 76°F.

And most importantly, what kind of disease did they come down with?

 

[San O Fisher]

my apologies on the swhwartz cory as I originally had them and switched out to sterbai who prefer warmer waters.  The tank is set at 83, which is more than fine for the discus and the cory.
 
Regarding the disease it was a skin parasite that cuased them to shed the slime coat and skin.  From infection that i could see to death it went very quick.  Once I got the remaining 3 in a salt bath they bounced back super quickly and are fine. 
 
I have heard though you can use very low doses of salt for a short time, but didn't know what was a low dose.  I do not want to hurt the corries and especially my pleco who my kids named.

 

[Akasha72]

seconding RainboWBaco's post. Cories can not tolerate any salt at all - the same for the pleco. Please don't let them come into contact with salt