The Walmart/Target stores in my area are all out of hth OTO chlorine testing kits (it's a short swim season here in Illinois). But I did read something in Taylor's manual about how to test for high levels: they suggested adding the 5 drops each of Reagent #1 and #2 into the vial and THEN adding pool water a drop at a time to see if there is any CL is present, so I tried this and the sample never turned pink.