The volume of your pool is roughly 14,000 gallons. In a pool this size, each quart of 6% bleach will raise the chlorine by about 1 ppm. With a cya of 40, you need to be shocking up to 15ppm. Test morning and evening and each time, add enough bleach to get the cl back up to 15. Also, brush the pool daily and run the pump 24/7. When you vacuum, are you moving the vac head very, very slowly? If not, you just stir everything up and that can cloud your water.