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
Pro: Having the reference solution takes a lot of guess work out of "is it too dark green, is it too light green???" Con: I've seen people have mixed success with filling the indicator chamber. I too found the bend rather challenging and the solution wouldn't easily go into the chamber (I ended up shaking the drop checker to finesse the indicator solution into the chamber). And when I did get the solution in, some of the solution actually got stuck in the bend leading to the indicator chamber. That meant the chamber stayed blue because co2 gas was prevented from reaching it. I solved it by blowing into the drop checker to clear the blockage. It's all good now! Side note: this isn't my first drop checker as I have the ADA one. The ADA one is much easier to fill.
I got this because I was tired of second guessing the color of my drop checker. "Is it too yellow, shouldn't it be greener, does the tint of my aquarium glass affect the color?". Having the reference color available makes it so much easier to gauge the co2 levels in my opinion. And it just looks cool. Highly recommend!
Both required solutions are premade and included. Took a little patience to fill the top chamber. I love that it eliminates the ambiguity factor. My only complaint is that it is a bit expensive for what it is. My only suggestion is to offer a model that uses magnets instead of a suction cup. Staff Reply: Thank you! The reason these are so expensive is because these are hand made. Think of them as one off art pieces. Literally no other brand or type even compares to quality or design. The magnet idea is really cool!
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.
Works like is says, it does change color in response to co2 that's dissolved in the water. It's not hard to refill.
The drop checker really is a piece of art. It seems to work well and looks great in the tank. Only reason I didn't give it 5 stars is the bend into the upper chamber is too narrow and makes it a frustrating chore to get the liquid in and out of it, let alone cleaning.