The Aqua Della Multi test 6 in 1 is a tube containing no less than 50 test strips. With each strip you measure the 6 essential water values: nitrate, nitrite, total hardness, carbonate hardness, acidity and chlorine. The strips are easy to use and within 60 seconds you can compare the values using the colour scheme on the tube. The test strips can only be used for freshwater aquariums or ponds.