CAL Double Check CO2 Checker

Cal Aqua Labs’ “Double Check” series is the only all-glass dual-compartment CO2 checker that allows the user to accurately compare the CO2 level in your aquarium side-by-side against a standard reference. The top chamber holds the CO2 indicator solution, whereas the bottom chamber carries a CO2 reference solution. The reference solution color corresponds to 30 ppm of CO2 – a level that is widely accepted for good plant growth in most aquariums.

No more guessing on the shades of green. No more looking back-and-forth at color sheets to compare. You know the precise CO2 level simply by comparing the colors in the two compartments side-by-side. Don’t guess, be sure! It’s as simple as that.

• Unique dual-compartment design. Inner compartment holds the Reference solution, while the outer compartment holds the Indicator solution
• No solution preparation needed. Required solutions are premade and included
• Improved durability and ease of use
• Easy to fill and remove solutions from both chambers
• Simple to use, simple to read, higher accuracy than other single-compartment checkers

Each set includes:

• 1 Double Check CO2 checker
• 1 x 15ml Reference solution, calibrated to 30ppm CO2
• 1 x 15ml Indicator solution
• 1 suction cup
• 2 Reference chamber plugs
• Use instructions

Approximate size without suction cup: 2″x 1.5″ (WxH)
Recommended for aquariums 20 gallons and larger.