I have TFTtestkits.net CYA view tube test kit. I consistently get around value of 65 (I have an SWG). The R-0013 reagent is fresh. I brought the water to Leslies and the value was 100 on the slide test they use. I looked at the sample myself and was in agreement with their reading. Why is there such a large discrepancy between the results? Which is more reliable?