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Cal Aqua Labs Pearl CO2 Drop Checker

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Cal Aqua Labs' PEARL is a 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 unique space-saving design places the reference chamber right inside the the indicator chamber. The inner chamber holds the CO2 reference solution, whereas the outer chamber carries a CO2 indicator 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. Simply adjust your CO2 level so that the color of the indicator solution matches that of the reference solution. Don't guess, be sure! It's as simple as that.

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

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

Approximate size without suction cup: 2"x2.3" (WxH)


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

Customer Reviews

12 reviews

  • 5

    Everybody is right, Cal Aqua Labs is the absolute best in the hobby.

    Posted by Lee Parsons on 3rd Sep 2021

    I was debating this vs the cheaper ones but Im so glad I did. Opening this out of the box I knew right away it was premium quality. Pictures do not due justice. Its so nice I want to hang these on this years Christmas tree but my wife would destroy me.

  • 5

    The highest quality drop checker you will find.

    Posted by Omar Dennison on 29th Aug 2021

    This is fact. Ive used so many cheap glass drop checkers and after all them breaking in some weird form or another I invested into GLA's Cal Aqua Labs drop checker. I did not know it was this high of quality. People, Cal Aqua labs makes artisan piece of aquarium glassware. This is not your mom and pop shop level of glassware. I own ADA and VIV glassware and Cal Aqua Labs make them look like cheap knock offs. Especially the VIV glassware which still cost me a lot. Comparing the two is ridiculous. VIV glassware is as if a child made it, warped and nothing is straight. The ADA blows VIV away, but the new version I have is nothing like the old version from 2007. I dont know why, but totally different now. If you can afford it go with Cal Aqua Labs, you will be impressed, I surely was.

  • 5

    co2 drop checker

    Posted by dave on 20th Aug 2021

    excellent product that adds class to tank.

  • 5

    Simple, easy to use

    Posted by Amber on 1st Aug 2021

    Directions are straight forward. I appreciate the idiot proof nature of the inner bubble

  • 5

    Pinnacle of aquarium glassware.

    Posted by Jesse Armstrong on 25th Jul 2021

    If your reading this review its because you landed on Green Leaf Aquariums drop checker page because its the best there is. This is no joke, you will absolutely not find higher quality well made designs anywhere. Craftsmanship is artisan, quality is clearly paramount at Cal Aqua Labs because nothing comes close to this level of quality. The knock off glassware is just absolute junk. You can tell when you see junk just by how crooked and lopsided everything is. Well, not with Cal Aqua Labs. I shit you not, its a premium price and your getting actual true artisan glass. Even my wife was impressed and she has no clue what she's even looking at. Thats all you need to know.

  • 5

    Co2 checker

    Posted by Kelly on 24th Apr 2021

    Beautiful/functioal, shipping communication was great, arrived on time!

  • 5

    Top of its class

    Posted by Raphael Santiago on 18th Mar 2021

    I have many drop checkers and Cal Aqua Labs drop checkers and glassware in general is the best. Make no mistake, this is the highest quality glassware available. From design to the flawless packaging.

  • 5


    Posted by Rob Cook on 1st Sep 2020

    Great product! We have to use a drop checker. Why not make it one that has the reference color built into the checker. A win, win situation.

  • 5

    Pearl Drop Checker

    Posted by John Killby on 19th Aug 2019

    Very easy to correctly set CO2 levels having the reference media inside chamber

  • 5

    Very Nicely Made

    Posted by Jake Snyder on 8th Aug 2019

    A beautiful product, with simple instructions that allows for a quick install. This adds an easy way to my tank for checking CO2 levels. It’s been up and running for a day now, but it looks great. I do wish the instructions included information on how often you should refresh the solutions or if they never need to be changed.

  • 5

    No more guessing

    Posted by Bill Monk on 2nd Jul 2019

    Simple to use and makes it easy to fine tune your CO2. Highly recommended!

  • 5

    Drop checker

    Posted by Daniel Reyes on 11th Mar 2019

    Love my new drop checker, having the reference fluid in the small bubble is a great addition!!!

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