However for simplicity sake, most people do not have a way to convert or calculate PPM.
Ounces/gallon is easier although not as accurate. But the desired effect is still the same. Some salt is better than no salt. But it is relative to what plants you are growing as some plants simply will not do well with the salt.
I use this same salt treatment with many ornamentals, and have used it with a variety of ailments/treatments. Although I can't prove that the salt is the reason for the cure. There are simply other variables that could have contributed. However the point of my rambling is, is that 'salting' freshwater is a common practice and can be done a great many ways...so long as it's not iodized. So yes you can use table salt, if NON Iodized.