Review on 🐠 Glosso Factory Drop Checker Kit: Single or Dual CO2 Indicator for Planted Aquariums - Pre-Mixed 4.2 and 8.4 dKH Solutions by Dominique Robinson

Works as advertised arrived in good condition and works. First I started too high in the tank and didn't get a proper reading. Make sure it is at least 4 inches below the surface. Blue means low CO2, green is ideal and yellow means high CO2, sometimes high readings. looks like a perfect read, but after watching it fluctuate for a few weeks you'll get used to it.