Assuming you're starting salt free, #80 of salt would add 355.4 ppm to your 27,000 gallons. The bleach calc program will figure this for you. If you don't have it, I suggest you download it.

You probably won't notice any difference in water feel at that low a level. I am a bit over 1100 ppm, and the water feels much better. Lot's of threads here about adding salt and the differences it makes.