The test kit is designed to test the most important markers in your freshwater aquarium to ensure healthy water for your fish. The test allows you to easily and accurately determine the following levels: *Carbon dioxide * Carbonate hardness (KH) * Acidity and alkaline (pH) * Ammonia * Nitrates & nitrites. Although your aquarium water may appear clear harmful levels may be present which can increase algae growth and harm your fish and plants. The JBL online laboratory provides easy to follow comparative analysis to help you understand the readings.