Review on S T International Aquarium Indicator Reagent by Jennifer Wilson

Comes with very few instructions and only includes instructions for use with the ST International Long Term CO2 Monitor (sold separately). The label on the bottle contains instructions for use. The aquarium water is filled up to the line of the long-term monitor and then 5 drops of the indicator solution are added. I didn't buy the long-term CO2 monitor from ST International because of the price and the loud look. I did a little research and found recommendations to use 4dKH water instead of aquarium water. If your aquarium water is more likely to be okay if it has 4dKH. The water in my aquarium has a carbonate hardness of 2 dKH, reverse osmosis (RO) water has 0 dKH and tap water has 9 dKH. I ended up mixing a solution of tap water and reverse osmosis water to make a 4dKH solution. It consisted of 40 ml tap water and 50 ml reverse osmosis water. I stirred and left it alone as it would take time for the carbonates in the count water to dissolve and even out with the added reverse osmosis water. I then mixed 3ml of this 4dKH solution with 4 drops of CO2 indicator solution. When you mix them it should turn dark blue. You can add this solution to any CO2 reduction tester (monitor) you have.