I had a problem with the Seachem Alk test kit - brand new. It was reading 1/2 of the correct value. They sent me out some new reagents VERY quickly and free of charge. I loved the fact that they acknowledged the problem and fixed it. While I prefer the Salifert kits, the really cool thing about Seachem is that they also include known samples to test the reagents! That's how I found the problem.