Be confident in your purchase we're an Authorized Coral RX Dealer. How cool is that?!?!? Features: Accurately and immediately measures hardness and alkalinity levels in aquarium water. Detects carbonate and bicarbonates found in active aquarium setups. Performs up to 100 tests for repeated use. Changes color when it detects even minor fluctuations. Helps you maintain healthy water for aquarium setups. Your marine friends need safe, toxin-free water to grow and thrive in, so make sure their home is safe with the Salifert Carbonate Hardness / Alkalinity Aquarium Water Test Kit. Fintastic for measuring the amounts of carbonates and the hardness/alkalinity levels in your aquarium?s water, this test kit can accurately and immediately perform checks up to 100 times, meaning you can rest easy knowing your pals are swimming in safe water for a long time to come. These tests change color to detect even minor fluctuations so you can find them early on for vital intervention as needed so your fish, plants, and other marine friends can swim about happily and healthily.