Pickling and canning salt is the very best, because it doesn’t have any additives (calcium silicate) to keep the salt grains from sticking together. Avoid kosher salt, because the anti-caking
agent may cause a strong burning sensation in your nose.
The best saline solution has the ratio 2 grams salt for 98 milliliters of water. This is about 78 grams of salt to the gallon. Do the math, and make it practical, it works out to be 10 teaspoons of salt poured into one gallon of distilled water.