1-1/2 lbs. will add about 10ppm. Try that first which will put you at 40. Don't test for it again for a week after you add it to make sure it is totally dissolved.

However ....... I see that you have a chlorinator Are you still using trichlor tabs? If so, they have CYA in them so you won't want to add any additional CYA. If you do use the tabs, you will need to monitor your CYA level so it doesn't get too high and also monitor your pH level. They are very acidic and will drive pH down. (Also, make sure your tabs don't have copper in them.)