Cal Aqua Labs

Cal Aqua Labs Double Check Drop Checker


Current stock: 0

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, the bottom chamber holds 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.

This innovative drop checker is designed to be efficient and accurate, implementing a simple visual comparison of the CO2 level in one's aquarium with an optimal CO2 level, indicated by the standard reference solution. The Double Check drop checker eliminates the guesswork normally involved in determining which shade of green is considered optimal, and reduces the need for color comparison references. The precise and prime CO2 level is achieved when the colors in the two compartments are identical.

The Double Check is hand-crafted using only the highest quality, laboratory-grade, borosilicate glass for maximum strength, durability, and visual clarity. Each piece is unique.

Top Compartment - "Indicator" solution

Bottom Compartment - "Reference" solution

No solution preparation required. 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

Approximate size without suction cup: 2"x1.5" (HxW)


One (1) Suction Cup

One (1) Bottle of CO2 "Indicator" Solution (15 mL)

One (1) Bottle of CO2 "Reference" Solution calibrated to 30ppm CO2 (15 mL)

2 Reference chamber plugs

Instructions for use


3 Reviews

Todd L Rhodes 15th Nov 2019

Wicked good

Very nice piece. Could only find this in the UK. Chuffed I could get it in the USA. This thing is perfect. Best part if it is the fact that within 30 mins it will already be showing you what your levels are. Others take 1 or 2 hours which can be misleading.

Melinda 5th Oct 2019

Nice co2 checker

Works like is says, it does change color in response to co2 that's dissolved in the water. It's not hard to refill.

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