I have a 18' round 52" pool and a intex SWG. I checked the salt level before adding any and it says 470 ppm. I'm not sure how much to add. I have 5 40lb bags of pool salt and I added 4 bags this afternoon. I think that another bag might be too much but then again this will be my first season with the SWG and I have no clue what to do.