Glass CO2 Drop Checker – CO2 Monitor Kit for Aquarium Tank – Functional and Reliable – Transparent Drop Checker, 4dkh/pH Reagent Solution and Suction Cup

I’ve been using this drop checker in my planted tank for about two weeks now, and I don’t really have any complaints. It’s a small thing, but it does what it’s supposed to without getting in the way — which is more than I can say for a few other ones I’ve tried. First off, the design is clean and compact. It tucks neatly into the corner of the tank and doesn’t draw much attention, which I like. It comes with everything you need to get started, including the indicator solution and a pipette. The instructions were actually super clear — one of the few times I haven’t had to google a setup video just to make sure I was doing it right. I noticed the color change after a couple hours and it’s been easy to read since. The green shows up clearly through the glass and gives me a good sense of where my CO₂ is sitting throughout the day. So far, so good. That said, one thing to note — if you’re using a CO₂ system without a built-in drop counter, this won’t replace that. You’ll still need a separate bubble counter to dial in your injection rate. The drop checker tells you what’s going on in the tank, not what you’re actually dosing, so it’s more of a confirmation tool than a control one. What I Like: • Small and low-profile • Clear and simple setup • Comes with everything needed to start • Easy to read color change Heads Up: • Doesn’t function as a drop counter — you’ll still need one if you don’t already have it Overall, it’s a solid little tool for keeping an eye on CO₂ levels. It does the job without being bulky or confusing, and at this price point, I think it’s worth it. Would recommend if you want a reliable visual check without spending a ton..

The drop checker was extremely easy to use, I just added the liquid inside flipped it over and pushed it into my tank. It took an hour or so for the color to change and stabilize itself to the CO2 in my tank. This is perfect for tanks that was to measure their CO2 to make sure their plants are provided with the nutrition they need to grow. Not only that but it helps you control the algae growth in the tank by knowing how much CO2 is in there. One thing to note is that if you have a tank smaller than 3 gallons, it will a lot of the space. I currently have this in my 2 gallon tank and it is very obvious and cannot be hidden as well, but considering the pros it brings this is nothing.

Came intact and works well. You need to give it a few hours to adjust

I’m glad I purchased this for myself as the one I received wasn’t in the best of shape. The outer box had gotten wet at some point (this was the only item in my shipment that had any sort of damage), the inner box holding the glass drip checker was completely open, and I’m not sure if it was supposed to come with a reference card or instructions as seen online or not, but I didn’t have one. There is a chart and some limited instructions printed on the drop checker box that I didn’t notice at first and very nearly threw away. I had to look online for information about where in the tank to place the checker, how often to change the fluid, etc. Other than that, seems to be of good quality and should work just fine.

No issues with this, liquid easy to get in, looks good and is easy to read in the right location. I think it would help to put white electrical tap on the back side to make reading it a little easier Update a month later - still good but to get a good read on it you really need it near the front of the tank and I’ve found half out of the water do you can get a good look at the color with influence of water coloration and back ground. This - and every other design - would be much better if the liquid ball was the think against the glass of the tank, not the spout

This Glass Co2 drop checker is a valuable tool to have in your tank. It's small and being glass it basically disappears in the tank and is NOT conspicuous. The monitor fluid goes from blue to green when the CO2 levels are proper and with a planted tank now that drop checker REALLY disappears! The drop checker has helped me several times as I was injecting too much CO2 so the green went yellow and even to clear once. I shut my CO2 generator down a day or two and the monitoring fluid went back to green and I turned the CO2 generator back on turning that needle valve down to about one bubble per second. Finally I got the needle valve to where the drop checker was green every day which is where you want to be. Do you ABSOLUTELY need this? No. But for me, it was quite helpful and I'm glad i bought it. Glad I'm using it. On a side note, I notice that in photos of a lot of really high-end Amano type tanks I see these little CO2 drop checkers so I figure if THEY are using them perhaps it would be wise that I use them as well.

A really well-designed drop checker, and it fits nicely in my 10-gallon tank. I was afraid it would be big and ugly, but it looks good, and I can always hide it somewhere in the tank. It comes with a solution (already premixed), so you don’t need to do anything—just put some drops in, and you’re good to go. The color changes are really noticeable; green and blue look truly different, so now my shrimp are safe

Glass came in fine and product worked for my CO2, however the liquid was at half when I opened the package and it looked to be spilled at some point. Liquid had spill marks but it was fairly dry so I don't think it was from this shipment.

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My only gripe is that the accompanying CO2 detecting liquid could have been more