I was testing a friends' pool today for alkalinity with the Taylor 2006c kit. I put the 5 drops in and the solution turned green, as it should. But as I added the next drops in, the green did not turn red, instead it turned blue and eventually to yellow! I am fairly new at pool testing, but in my own pool, this test always went good......turning from green to red. What gives????

A little background here: this pool is currently at shock level (Chlorine 25 ppm, CYA>100) because he is battling an algae bloom. Does a high Chlorine count affect the ALK test?