Your CYA will not go down much during the summer. Once CYA is in the water, the only way it is reduced is by splashout or draining and refilling of water. Frequent backwashes and a lot of splashout may drop it a little, but you'd have to lose 20 ppm or so to make a difference in how you treat your water--and that's not going to happen over a summer. So....you can leave the CYA at 100 and keep your chlorine in the 8-15 ppm range, and enjoy your pool!

If your overnight chlorine loss is less than 1 ppm, and the water is clear, then you can go ahead and let your chlorine start dropping, but no lower than 8 ppm at all times! Also, I would not use any trichlor pucks or dichlor granulated shock in your pool, they both contain large amounts of CYA and, while yours is manageable, you don't need for it to get any higher. I suggest you stick with bleach, if possible.

Janet