Determine calcium and magnesium in water samples for aquarium and aquaculture. The water sample can be freshwater and brackish water with the salinity between 0 - 5 ppt. It is designed to be compact size and allow to measure 120 times. The test can be performed simply, quickly and easily. This titration test kit first carry out the calcium test (0 – 200 ppm), which has a sharp color change, going from pink to blue when reach the calcium level in the sample. Then follow by the magnesium test (0 – 960 ppm) which also has a significant color change, going from orange to green, when reach the magnesium level in the sample.