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Co2
CO2 Drop Checker
A glass indicator that visually shows dissolved CO2 levels in a planted tank via colour change.
Price: Budget
For: Freshwater Essential gear $10-$40
📖 Overview
A small suspended glass chamber filled with 4dKH reference solution and bromothymol blue indicator. Blue = low CO2, green = ideal (~30 ppm), yellow = dangerously high. The essential tool for tuning pressurised CO2 injection.
🛒 Buying Guide
pH controllers offer more precise measurement but drop checkers give reliable visual feedback at low cost.