intersting. I have a Taylor k-2005 which uses the same pH reagent as the K-2006 (large comparator with 45 ml sample for pH test) and I have Ben's ps234s which has the Taylor pH/OTO test kit in it. I get basically identical results from the two tests. Are you sure you are using the correct reagents for each test? The pH reagent in the K-2006 (which I assume you have) is also used for acid and base demand tests and is different than the one in the K-1000 (or Ben's ps200) and if you use the wrong one you might get wierd results.