The 𝗩𝗲𝗹𝗱𝗮 𝗧𝗲𝘀𝘁 is one of the most accurate available in the world. Suitable for measuring pond and aquarium water.pH: With this professional pH test, the acidity of fresh and salt water can be determined very accurately. With the help of a color scale and a comparator, you can quickly gain insight into the values between pH 5.0 and pH 10.GH: With this professional GH test, the calcium/magnesium value of fresh water can be determined very accurately. With the help of a neutral disk and a comparator, you can quickly gain insight into the total hardness with an accuracy of 1 °DH.KH: With this professional KH test, the carbonate hardness of fresh and salt water can be determined very accurately. With the help of a neutral disk and a comparator, you can quickly gain insight into the carbonate hardness with an accuracy of 1 °DH.