If you're holding chlorine overnight, then go ahead and start raising your CYA. We typically recommend that people start with a target of around 40 ppm, and then once that level is reached, you'll need to evaluate your chlorine loss during the day to see if you want to go higher. You can add it through the skimmer and let it dissolve on your filter, but if you do that you can't backwash the filter for 4-5 days or you'll just wash the CYA out and have to start over. Or you can put it in an old sock and hang it in front of a return while it dissolves. If you're still needing to backwash to clear up your pool (which you shouldn't do until you see an 8-10 psi rise in pressure--remember that a dirty filter works better than a clean one..) then I would go that route.

Edit: Ben is apparently typing faster than me today........