CYA can only be measured in 10 ppm increments. So a 23 is rounded up to 30.I just checked CYA, at 30, you can barley see the black dot, and only if your standing directly in the sun. It truly disappears around 23.
You can stop testing CYA till after the SLAM is complete. It will stay there and not really change.
Great. Retest and add more chlorine. Remember Shock Level And Maintain.My FC was just at 11.5, I added a cup of 12.5%, last added some about 1.5 hours ago.
Remember to vacuum slowly and afterwards brush walls and floor. You don't have to vacuum to waste but the pressure will increase quicker. Vacuum to waste will dump a lot of water.