Double Points April - Purchase this item and get 
An easy to use and accurate kit used to measure Carbonate hardness (KH). For fresh & saltwater use
The carbonate hardness (KH) of aquarium water should be tested frequently, since water with a low KH is subject to rapid shifts in pH, greatly stressing fish and making them vulnerable to disease. This kit measures carbonate hardness (KH), the measure of carbonate and bicarbonate concentrations in the water. The proper KH level is an important part of water quality and is necessary for the health of fish and the development and growth of aquarium plants.
