CAL 60 ml Indicator Refill Solution

60 ml. Indicator refill solution for use with CAL AQUA LABS’s CO2 checkers. It consists of a premade 4dKH solution containing the appropriate amount of indicator.  Easy to use, no mixing required. Simply open cap and fill CO2 checker.  It is also more accurate than starting off with a regular 4dKH solution and adding drops of indicator separately.  This is because the additional liquid contained in the indicator drops will further dilute your 4 dKH solution, resulting in a final solution that is less than 4 dKH.