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CO2 Drop Checker Indicator Solution 10ml

CO2 Drop Checker Indicator Solution 10ml

Our Price: £4.49
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  • Accurately monitor the CO2 levels of your aquarium.
  • Easy to use 15ml dropper bottle.
  • Pre-made mix of 4dKH solution and drop check indicator.


This test solution is added directly to a CO2 Drop Checker.  Over a period of a few hours the colour of the solution changes to indicate the concentration of CO2 in the water at the time; blue indicates a lack of CO2, yellow indicates too much CO2, and green indicates the desired level of CO2. Depending on the colour of the drop checker you can adjust your CO2 dose until the desired level of CO2 is reached. 

The solution comes in a handy 15ml dropper bottle for easy deployment into the drop checker.


  • Empty existing indicator solution from drop checker.
  • Fill drop checker with solution until the chamber is 2/3 full.
  • Position the drop checker in the aquarium so it is visible, but such that CO2 bubbles from your diffuser do not easily enter the drop checker, which could result in inaccurate reading.
  • Wait at least 6 hours for colour to accurately reflect the CO2 levels in the aquarium.
  • Adjust CO2 dosing in accordance to drop checker colour:
  • If the colour of the solution is yellow it indicates too much CO2 is present - reduce your CO2 dosing.
  • If the colour of the solution is blue increase CO2 dose in small increments.
  • If the colour is a light green you have the correct CO2 dosing.
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