Review on Fluval A7551 CO2 Indicator Kit by Julie Lewis

When it comes to CO2 indicators, the choice is limited. I only chose Fluval because it was readily available from Revain. It was easy enough to set up. I added the indicator solution, turned it upside down and added it to my aquarium. It took a good 6 hours for the solution to turn green. Now I have no fish in the aquarium, only plants. It must work because one day I connected my CO2 tank but forgot to open the valve. There was no CO2 in my tank all day. When I got home from work, the solution was blue. The next day it was green again. I think the key is to be patient. It does not provide real-time results. Wait a few hours before adjusting the amount of CO2 and wait a few hours between adjustments.