Your going to need a lot of bleach...
Here are the instructions for the SLAM Process. Get pH down to 7.2 and start adding bleach.
Aim for 10 to start, about 3 jugs of 12.5%. Get some CYA/stabilizer/conditioner in a sock and float it out in front of a return jet, aim for 30. Once the CYA is floating in the sock raise FC to 12 and start brushing and squeezing the sock to dissolve the CYA.
Are you using PoolMath?
4 pounds of stabilizer in 40k gallons of water is only 12ppm of CYA. The test only goes down to 20 or 30ppm and is roughly +/- 10ppm.