Low CYA Chlorine Stabilizer

How much cyanuric acid (CYA) do I need add after I refill my pool with fresh city water to stabilize my chlorine levels ? I added 12 pounds of CYA and after 3 days I tested using Taylors K-2006 Complete FAS-DPD Chlorine Test Kit, and I am not showing any CYA in the water.

My pool is an in ground pool (12,000 gallons), the surface is shotcrete with a Compu Pool Salt Water Chlorine Generator CPSC24/CPA Series, and Pentair SuperFlo Pump. My pool has full exposure to the sun all day long, because I live in the Sunshine State (Central Florida). During the day when the pool is not being used, I put on a blue solar cover (12 mil) to slow down the SUV from killing my chlorine.

These are the test measurement I took last night, after running the pool for 5 hours after the sun low in the sky (4:00pm - 9:00pm) using Taylors K-2006 Complete FAS-DPD Chlorine Test Kit

Water Temp = 88 degrees F
PH = 7.2 ppm
Total Alkalinity = 60 ppm
Calcium Hardness = 130 ppm
Cyanuric Acid = 0
Chlorine = 1.0
Saturation Index = 0.73 (Taylors Water Balance Calculator)

Before taking these measurements, I tested the Chlorine Output level of the Saltwater Chlorine Generator. I tested the water just after the water pasted through the Generator and before the water enters the pool. The chlorine output of the generator was 10+.

However I can not maintain chlorine, and I do not know how much CYA to add. I don't want to put to much in, because I know that the only way to reduce CYA is to empty water from the pool, then add new water.

Please help me.
- dshehan2000