Flex 5600 econominder drawing air during brine draw

[cscracchi]

I replaced my 8x44 resin tank with a 10x44. At the same time I changed the DLFC from a 2.0 GPM to a 2.4 GPM. Changed the nozzle from red to white. Increased the salt usage from 9 to 12 pds. Every since air is drawn into the system during brine draw. This is known because there is air when flushing the toilet at the end of the plumbing line in the home. So I replaced the brine tank check valve and have manual confirmed it is working correctly. I did a rebuild kit also. Issue still exist. What am I missing? What should I try next?