24 foot round pool with a chlorine lock what to do?

Reduce the water level and refill with new water and do not use chlorine with stabilisers added until the level of cyanuric acid is reduced. Take a sample to the pool company and have them check it. The name of dichlor or trichlor on the chlorine tells you that there is stabilisers in it . It's good to have some cyanuric acid (not over 100ppm) because it prevents burining off of free chlorine by the uv waves in sunlight, but high levels are not good because it takes longer for the chlorine to kill micro-organisms. This is a non scientific answer and I am dealing with this issue myself. Apparently this builds up in pool water. Good luck.