Yup! No tabs, and lots (and lots) of bleach to bring your FC to >10% of that high CYA.

I have an auto-cover too, and if I have to add more than a quart of 12.5%, I usually wait 1 hour before I close the cover. The bleach just needs to circulate and dilute. So if you're still awake tonight, GO FOR IT!

I am not 100% positive on the following because your CYA is so high, but the auto-cover MAY be your pal in this situation. The auto-cover normally needs to be open only a minimum of 1-2 hours a day to get UV benefits. Keeping it closed more during the day will help you retain some of your chlorine. (Hope the experts chime in here if high CYA is a special situation....)

When you have time on your hands, I also suggest you read about the Nature 2 system and the "minerals" it adds to your water. Just a thought.