With FC that high you cannot be sure your pH isn't artificially raised. Try a couple of drops of chlorine neutralizer in it first (Taylor-0007--or the first two drops you put in when running the Total Alkalinity test--before adding the dye.

I personally don't like CYA that high--draining half your water and refilling will get it down to 70-75--high but much easier to manage. At 150, you need a constant FC of 8-15ppm.