Nutrafin's carbonate and general hardness test kit measures carbonate hardness (kh) and general hardness (gh) in fresh and saltwater aquariums. Carbonate hardness (kh) must be tested on a regular basis because it fluctuates over time and can negatively impact the ph balance of aquarium water. Low carbonate hardness will result in poor plant growth. Testing for general hardness (gh) should be done to determine if levels of calcium (ca) and magnesium (mg) are optimal for specific species of fish. The kit includes one 15-milliliter bottle of kh reagent, one 10-milliliter bottle of gh reagent, one glass test tube with cap, one pipette, one lab base, one instruction booklet. Measures 2-inch length by 5-1/2-inch width by 5-inch height.