Dear Lord, do not use salt to treat ich in your tank. The massive amounts needed to drop the parasite (which by the way won't leave the tank) would kill your fish first.
Use a medicine. That is to say you know what kind of ich you have. Increasing the temperature over 90 will take 2-3 days safely.
Unless you do a salt dip and return your fish, even still you need to treat the tank.
Here is more about ich:
Is it white spot disease or is it Ich? You need to know the difference between the two since they are treated differently.
Cryptocaryoniasis, White Spot Disease or Marine Ich is caused by an infestation of the ciliated protozoan Cryptocaryon irritans. Although Cryptocaryon becomes a parasitic organism at one stage in its life cycle like Oodinium and Brooklynella do, and it progesses less rapidly than these other ich diseases, in a closed aquarium system it can reach overwhelming and disasterous numbers just the same if it is not diagnosed and treated upon recognition.
Unlike Oodinium and Brooklynella that typically attack the gills first, which allows these ich diseases to advance into life-threatening levels quickly as they go unnoticed, Cryptocaryon usually appears at the onset as salt-sized white spots visible on the body and fins of a host fish, and when the organisms become parasitic, it is then that they move inwards to the gills. Because crypto is more easily recognized in its beginning stage, this makes it much easier to treat and cure before it gets out of control.
Aside from the appearance of the white spots, fish will scratch against objects in an attempt to dislodge the parasites, and rapid respiration develops as tomonts, mucus, and tissue debris clogs the gills. Fish become listless, refuse to eat, loss of color occurs in patches or blotches as the trophonts destroy the pigment cells, and secondary bacterial infections invade the lesions caused by the trophonts.
Although copper is very effective on Oodinium, and it works well to eliminate crypto organisms in their free-swimming tomite stage, it is not as effective on the Cryptocaryon trophonts that burrow deeply into the tissues of fish. A combination of freshwater and formalin treatments adminstered by means of dips, baths, and prolonged treatment over a period of time in a QT is recommended
Reinfection will occur no matter how effectively the fish have been treated if Cryptocaryon is not eradicated from the main aquarium, which can be accomplished by keeping the tank devoid of any fish for at least 4 weeks. For fish-only aquariums hyposalinity can be applied, and to speed up the life cycle of the organisms, elevate the tank temperature to 85 degrees for 10 days to 12 days. For treating reef tanks, FishVet No-Ich Marine, Ruby Reef Kick-Ich, and Chem-Marin Stop Parasites are Cryptocaryon specific remedies that are said to be "reef safe". Several days prior to returning fish to the main aquarium, clean all filtering equipment, change any filtering materials, and do a water change.
Remember to remove all filters media and turn off protein skimmers when treating for any types of Ich.
Although many over-the-counter remedies contain the general name Ich or Ick, carefully read the product information to be sure it is designed to specifically target and treat "Cryptocaryon"
Brooklynella hostilis - these protozoa reproduce asexually by means of simple binary fission through conjugation, which is why they are able to multiply so much more rapidly than Cryptocaryon (White Spot), and Oodinium (Velvet Ich), and why it can kill fish within a few days and even hours upon recognition
Most similar symptomatically to Oodinium, this too is a parasite that primarily attacks the gills first. At the onset fish may scrap up against objects, rapid respiration develops, and fish often gasp for air at the surface as the gills become clogged with mucus. Fish become lethargic, refuse to eat, and colors fade, but the most noticeable difference that sets Brooklynella apart from Oodinium is the heavy amount of slime that is produced. As the disease progresses a thick whitish mucus covers the body, usually starting at the head and spreading outward, skin lesions appear, and it is not uncommon for signs of secondary bacterial infections to arise.
Suggestions range from copper, malachite green and other remedies, with some recommended being used in conjunction with formaldehyde. However the general consensus is these types of medications are either largely ineffective or do not work at all, and that the best and most effective treatment for Brooklynella is formaldehyde alone. Typically a standard 37% formalin solution (shop & compare prices) is mixed with either fresh or saltwater in a separate treatment container, initially all fish are given a quick dip or a prolonged bath, followed by continued treatment and care in a QT. Of course the longer fish are exposed to the formalin treatment, the more effective it will be at eliminating this "disease". Whether to administer a dip or a bath to start with is something you will have to determine yourself, but there's a very simple way to do this.
Since these are Free swimming parasites which are in watersources, come attached to our fish etc. The only way to ensure NO ICH is to get a UV Sterilizer and addit to the tank. The UV Sterilizer kills the free swimming forms of various ich and other parasites.
Hope this help
If the swarmers do not find a fish host, they die in about 3 days (depending on the water temperature).
Therefore, to treat it, medicine must be added to the display tank to kill free-living parasites. If fish are removed to quarantine, parasites living in the tank will escape the treatment -- unless ALL fish are removed for about a week in freshwater or three weeks in saltwater systems. In a reef tank, where invertebrates are sensitive to ich medications, removing the fish is the only option. Some people think that ich is probably dormant in most tanks. It is most often triggered by temperature fluctuations.
Salt does not kill ich. If that were the case, marine fish would not get ich.
Garlic soaked food which you can do on your own will help prevent ich.
And yes RyanD is right, any salt will do since ALL living creatures need iodine to survive.
Also, adding an airstone will add little to NO dissolved oxygen to your tank. Dissolved Oxygen which fish breath only enters the tank in the form of air movement against water. Even the little bubbles popping at the surface do NOTHING. You need waterfalls, (Filer) powerheads, waves fountains etc. Not air stones They are Decorative only.