Dymax Crystal CO2 Indicator - Small

Easily monitor CO2 levels in planted aquariums with the Dymax Crystal CO2 Drop Indicator - made from high-quality glass. Simply add the pH reagent solution (sold separately) to see if CO2 levels are optimal, excessive, or insufficient. Package includes glass drop checker, suction cup, and dimensions of 2" x 1" (small) or 2.5" x 1.2" (large).