If you do go with a combination of salt and heat (the only treament I will use any more), remember that as the water temp rises, the dissolved oxygen content of the water drops, so add an aerator when bringing the temp up over 81ºF.
I also have had success with salt/heat in the past. So that is what I have started today. Needless to say, I wish I didn't have to do it. Already lost one of my new tetras.