Very good test laboratory with all the important tests that you constantly need. Explanation is easy to understand tips about individual water values and for their adaptation are also listed easily understood. The test results are relatively accurate. Reading the color cards is but partly not always so simple. For not so good, I think the plastic cuvettes. These get through the test quickly and discoloration edges, which can be difficult to remove. Glass would be better. A critique point is the NO3 test. The really tiny vessel for the necessary testing powder is undersized compared to the corresponding test liquid and consumed quickly, while the rest is still nearly full and countless tests would be possible. The drop test you can then throw away, because when ordering you back the same problem and an excess of test fluid. This is also equal to the support of Tetra called. I had kind described my concerns and got more or less to say that unfortunately this is so and we can not do anything. By the manufacturer I would at least expect to receive a free sample of the powder and a little more ease. Here I draw like the comparison with JBL. When everything is perfect support and customer-oriented. And thus they would like to buy back, at Tetra I can not say this is currently .....