Quote Originally Posted by KurtV
There's at least one potential problem with using tap water as your diluter. The CYA test is basically a turbidity test. Any turbidity in your tap water will add to that resulting from the interaction of the test reagent and the CYA in the pool water and may give you an inflated reading. (I think.)
If that were true, then wouldn't most CYA tests would be invalid since tap water is used as fill water?