I was liking Tom until he said "Chlorine lock". No such thing. Go to the Best Guess table and you'll see that for 90-100ppm of CYA (stabilizer) you need to keep your chlorine at 8 to 10ppm, and shock it at 25. That's all, and you do NOT have to drain. If you drain half your water and refill, your CYA will be 45-50--and you STILL shouldn't use tablets then either--they add CYA.

That's fine, but you can't use the floater with the tablets any more. Use Liquid Chlorine or laundry bleach (same thing) for you chlorine--it won't add CYA.