Anna,
You'll need to check the Best Guess table that Lisa referred you to:

http://www.poolsolutions.com/gd/best...e-chart.html#a

With a CYA of between 60 and 90 (you have 80ppm), maintenance FC levels are 5-10 ppm, and shocking level is 20ppm. I personally prefer to be closer to the top of the range, since your CYA is closer to the top--say, FC at 7-10ppm.

But you'll see once your pool is clear where it "likes" to be maintain clear water.