I'm hoping someone can help me! This is my 4th Season and you would think I could get me chemicals straight, but with every other pool store telling me something different, its tough. Two years ago I stopped using traditional chemicals with the exception 3" chlorine tablets. I used copper sulphate one time in the beginning of the season, Biocarbonate (which I thought was for the PH, but after reading this forum I think it is for the Alk.), and bleach for chlorine. This year everything is pretty good but i can't seem to get the chlorine levels up. I have tried bleach (as much as 6 gallons), and cal/hydro powder (6 pounds- per pool store reccomendation). I checked it again this morning and the PH is a little low (6.8) and the chlorine is still reading 0. can someone please advise what I'm doing wrong. 18,000 gal pool, vinyl liner, sand filter. Also, what should I use to raise the PH up a little. I appreciate any and all comments.

Thanks Y'all