Taken from an article:
The salt and heat treatment is one method to treat ich. There are several meds on the market which are also effective against that parasite.
Slowly increase temperature to 86-88F (1-2 degrees per day) and keep it there for 2 weeks. Temps in the low 80s increase the reproduction cycle of ich which will increase the quantity of free swimming ich organisms in the water columnn (which are vulnerable to meds) but at 86F+ the temperature will interfere with ich reproduction cycle and also kill the organism.
If your go the salt route which I've never done for ich but have done for columnaris you will add salt like this (slowly increase the salt concentration to 1 tablespoon per 5gal of tank volume (1 tablespoon=3 teaspoons). So say you have a 125gal you need to add approximately 25 tablespoons, which amounts to about 3 cups. Dissolve 5 tablespoons of salt in a small cup or container of tank water and add that to the tank every 5hrs until a total of 25 tablespoons has been added. Never add dry salt directly to the tank the use 'aquarium' salt is not needed you can use Kosher salt do not use table salt.
This treatment will the lower oxygen content level in the tank water, so bring out the extra aeration or water surface agitation if you can (though if your fish are small it might not make much a difference, but definately do so if you've got 5" or larger fish). Maintain the salt and heat until 10 days after the ich was last seen on the fish, to ensure all the organisms have been killed. If you do a water change during this period, you'll have to replace the salt. So, for example, on day 8 you do a 25% water change, you'll have to add 6 tablespoons of salt along with the replacement water (keep track of how much salt has been added at all times).
I will add that MOST times the HEAT ONLY treatment will do the trick. If it were me, I'd start by raising you temp first and see how that goes after about 5 days. If nothing else salt can be added later.
Let me further add that the use of salt has been debated widely. Salt will harm other fish like loaches and catfish so if you have those fish or other fish that may less tolerable to salt the I'd forget the salt method all together.
I'd try and stay away from meds if possible. I had to heavily dose my tank with meds for 10 days with my bout with columnaris it's not fun.
I'm not an expert by any means. This what I've researched and what I've seen others do.
Good luck