Rhinox Glass Drop Checker Kit &ndash; 3 Seconds to Read CO2 Levels - 3 Minutes to Setup - Fastest Way to Ensure Sufficient Co2 in Planted Aquarium - Color Change Reflects the Level of CO2 HIGH-QUALITY, MUST-HAVE KIT - - - The Rhinox Glass Drop Checker is every aquarium/planted tanks essential tool. Keep the CO2 levels in your tank consistent by checking it regularly. This complete kit contains 1 glass drop checker, 1 suction cup, 1 10ml CO2 indicator solution, 1 2ml syringe and 1 colour chart. Please note: This kit does not come with the dKH Solution. EASY TO USE - - - Make sure your test kit is clean. Drop 5 drops of CO2 indicator into the glass checker and make sure it is stored in the bulbous side of the valve with the opening facing down. Attach this to the side of your tank, completely submerged in the tank water and wait for up to 2 hours. COLOUR CHANGE SHOWS RESULTS - - - Follow the color chart carefully. The CO2 indicator is blue in colour. When it turns green, thats the right balance of CO2. If it turns yellow, your tank has too much CO2. Make the necessary adjustments and test until you get green. BENEFICIAL LEVEL OF CARBON DIOXIDE - - - A healthy tank has a carbon dioxide to water level that contains anywhere between 20 to 40 ppm (parts per million). 30 ppm is the optimal level that is healthy for both plants and fish. Keep CO2 levels optimum for all your aquatic plants to grow lush and beautiful.