For OP, or anyone who reads this thread in the future, dont be scared for OCCASIONAL use of tabs. While you have to be aware of the CYA consequences. As was said earlier, if you go on vacation, a tab here or there will keep the water clear and chlorinated while away for a week, and not crush your CYA overall total is just used for that rare occasional use. ust do not use daily/weekly on a regular basis. like mnauss, I also buy the cheap individually wrapped ones to keep them until needed. For my midwestern summer, I go through maybe 3 pounds of tabs per summer. Of course we get so much rain here, we get a lot of water turnover.
Use the App/pool math calculator, and enter in your gallons of water,and state that you will add 8 ounces of Trichlor, and it will tell you how much CYA you are adding. For my 20,000 gallon pool, each 8 ounce tab does the following: it raises my FC 2.7 and CYA 1.7. So for a 1 week vacation, I use 2 tabs that will drip out about 1 unit of FC per day, and the total CYA increase of 3.4 is manageable since this is occasional.