Rhinox Co2 Indicator Solution (2 pcs) - Glass Drop Checker Replacement Solution for Aquarium - 3 Drops tell precise CO2 level in Planted Aquarium - Easy to use regent - Keep plants and fish healthy KEEP CO2 LEVELS CONSISTENT --- Keep the CO2 levels in your tank consistent by checking it regularly. Purchase replacement solutions regularly to ensure an accurate result every time you test. The 2 bottles by SunGrow ensures that you have the checker solution handy at all times. MAINTAIN BALANCE OF THE AQUARIUMS ECOSYSTEM --- A healthy tank has a carbon dioxide to water level between 20 to 40 ppm (parts per million). But 30 ppm is the optimal healthy level for both plants and fish. Making sure the CO2 levels are constantly comfortable for your aquarium life is critical. CO2 indicator can make it easy to test the CO2 level. It is now easier to keep and maintain an ideal CO2 levels through the use of CO2 indicator, the solution is a must have for all aquarium owners. EASY TO USE --- The CO2 indicator is blue in colour. Simply mix it with tank water, as per the label instructions and leave it in your tank for 1 hour. When it turns green, thats the right balance of CO2. If it turns yellow, your tank has too much CO2. Make the necessary adjustments inside your tank and test again until you get green. USE FRESH co2 REGENT --- Bottles that has been stored for more than 3 months might be contaminated by outside air. Fresh solution is advisable to use each time you test the CO2 levels. Discard the old bottles to ensure your CO2 indicator remains accurate. COMPLETE VALUE FOR MONEY --- This value-for-money pack contains 2 bottles of CO2 test solution gauge of 0.5 oz each (10ml each). Since it is NOT a concentrated solution, you can use it right away. Please note that the drop checker apparatus is not included and sold separately.