Colombo CO2 Indicator

  • Stock: 7 units in stock
  • Materials: Plastic
  • Dimensions: 3x1cm
  • Model: A5020295
Qty :

Skills Required
CO2 Requirements

Better together


CO2 indicator which measures CO2 levels in your planted aquarium.

If you never test, how do you know? Making sure you have good CO2 levels is so important in a planted aquarium, it cannot be stressed more. Quite often hobbyists guess or assume it's OK when the realisty is that it rarely is. This drop checkers lets you know what your CO2 levels are all of the time giving you peace of mind.


  • Easy to read
  • Stylish design
  • Contains enough indicator for 2 years
  • Contains free clear suction cup
  • Very simple set up (takes seconds)

The drop checker is a relatively new invention and previously test kits were used. However, they only measured the levels at the time of the test where as the drop checkers measure it 24/7.

It's amazing the difference the way your plant will respond when you have the correct CO2 levels and this Colombo CO2 Drop Checker will be one of those tools that you won't believe you lived without for your tank.

An absolute must for any planted aquarium tank.

also purchased

by Trevor Whitlock
Easy to install and gives clear indication of CO2 levels. Really glad I bought this as I am a CO2 novice, and I was worried that I was going to upset my fish. It has reassured me that the right amount of CO2 is getting into the water to keep both plants and fish happy.

by Tom Crorken
thank you very much. very fast delivery and works well. Tom.

by Michael Mathews
I'd been merely estimating the CO2 levels in my tank based on the bubbles-per-second going in for months. However, after setting up the Flora-Grow CO2 Indicator (which was extremely simple) I was quite surprised to see that the amount of CO2 actually making it into the water was way too low. I tweaked up my CO2 flow over a few days, and finally got the indicator to go green -- turns out I had to actually double the CO2 rate to accomplish this! And yes, my plants have all responded with gratitude. I never would have risked doing this however without an indicator -- it goes yellow when the levels are too high for the fish. Now that I've used this, I would never inject CO2 without an indicator again. This particular model is a little utilitarian in its design, not ugly by any means but I've seen more artistic models. At the end of the day this does exactly what's required of it and the 2 year supply of indicator solution is a particularly nice bonus.

by David Galer
I was amazed at just how low my CO2 was, if you use or intend to use CO2 it is a must. DG

Ask a question about this product
Hi, I bought this on your site and lost the instructions of how much blue liquid to add when refilling it, if you Could inform me, that would be great, much appreciated, thanks Stephen.

Fill up your drop checker about half full. It doesnt actually matter though so whatever is enough so you can see it clearly :)

Should I use bromo blue with this?


It's always recommended yes. The solution that come standard with it is alright but no where near as accurate as bromo blue. If there's one measurement you DO NOT want to get wrong in a planted aquarium, it's your CO2 levels.

Hello, I bought this to accompany my new Fluval 88g co2 system as I've recently converted from liquid co2 to the gas canister. I've had it running in there for about two days now (actively seeing the co2 bubbles floating around in the tank so it does work) and the counter still shows blue even though the canister shows a drop of 1mm on the reader since then AND I've placed it directly above the diffuser to check it responds. Is this not the right checker for this system or do you think I have got to wait a few days for co2 to saturate the water for it to make a visible change to green? My tank is 90ltr and has been starved of co2 for quite a while as its very well planted, but I just want to make sure I'm not now polluting the fish. Thanks :)


if your drop checker is not turning green, you simply don't have enough CO2 - simple as that.

Try 1 bubble per second and go from there.

I bought this recently and I’m using the solution that came with it...only after several days, I’m finding that the solution becomes diluted and disappears so it’s completely clear in there? Almost like it’s been washed out? I’ve tried it in different locations within the tank and it’s still doing it? Am I doing something wrong or is the solution not very good?


The solution is not very good. Use our Neutro Bromo Blue instead.

I have tried using this for a few days now, each time I half fill the checker within two hours it has leaked out. I can see it creeping up the bubble and exiting from the slot in the rear. What am I doing wrong?


is there a loose seal perhaps?

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