Carl's got you on the right track, and my kudos too, for doing your homework. The only piece of advice I'd add would be to add a small amount of straight stabilizer (maybe enough of a dose for 10-20 ppm?) as kind of a "loading dose", then let your pucks bring it up to where you want it. The problem is that it will take several weeks before the pucks are able to put enough CYA in the water to actually hold a chlorine residual.

Janet