Detection limit for Wal-Mart kit CH test??

[waterbear]

There has been a problem with the walmart hardness test that has been documented in a prevoius post by several people including myself. I suspect that it is being caused by high chlorine levels interfering with the indicator used in this test. A work around that I have used is to keep adding drops of indicator until the water turns either pink indicating hardness or blue indicating totally soft water. I have had to add up to 15 drops. this does not seem to have much effect on the titration results.