Pressurized CO2 for Beginners: Setting up your first CO2 system in a planted tank aquarium

CO2 Tank

What is pressurized CO2?

Pressurized CO2 is another one of the “Essential Components of the Planted Tank

Along with the other two components, light and nutrients, CO2 is absolutely essential for many of the High Tech plants you will find yourself attempting to grow. For more information on the Backbone of the Planted Tank see this article and infographic.

I will take you step by step through the confusing process of setting up a CO2 system, and I promise you will come out the other side with a better understanding and the confidence to drop the big bucks on the system you’ve been saving for.


Let’s get started.


Setting up your first Pressurized CO2 system

First and foremost, you need to find yourself a CO2 tank. You can either order online or you can buy your tank locally. I ordered my first CO2 tank online through a beer distributor. For about $20 I received a 5lb refurbished and empty tank. Not bad at all, and note – if you go the local route you will most likely be purchasing a new tank. New tanks run over $100 so if your budget is tight this might not be the most prudent decision. (NOTE: 5lb tanks are ideal and should last a 40 gallon tank a little over a year.)


Okay, you have your empty tank, now what? Now, you need to get your tank filled with CO2, so let’s hit up Google.

Google: beer supplies + (your zip)

Google: fire safety equipment + (your zip)

Google: welding supplies + (your zip)


Make a list of places closest to you, call them and get a quote on refilling a CO2 tank. It should run you about $20 for a 5lb tank.


Next on the list for your pressurized CO2 system is a pressure regulator and solenoid. Simply put, the regulator is the bridge between the CO2 tank and the aquarium, and the solenoid is the valve allowing the CO2 to pass through. When the solenoid is activated it opens up and the CO2 runs into the aquarium, when the solenoid shuts off it closes and locks up your system. Once again check your local CO2 suppliers as they may have used regulators for a steal. I own an AZOO Regulator and Solenoid. It is a budget system but I highly recommend it. If you want something with a little more prestige the AQUATEK Regulator and Solenoid combo currently sits on Amazon with 4.5/5 stars.


Check out AQUATEK Regulators and Solenoids


How do we leverage this system? Simply purchase an inexpensive outlet timer from your local home improvement store. I will explain to you the details further into the article with a visual guide.


Now we’re moving on to the less expensive and less confusing pieces in the build.
Find yourself some CO2 Proof airline tubing, enough to run from your tank to the inside of your tank. Next up is the bubble counter. I prefer using a brass (CO2 proof) screw on bubble counter as it keeps my system looking clean.

Finally, and perhaps the most important part, is the way in which we diffuse the CO2 into the water.

This is called our Diffuser. Let’s look at our options.


Methods of Diffusing CO2 (from BEST to WORST):

External Reactors /Atomizer– they work with your Canister Filter by hooking up to the output line of the canister. From there you plug in your CO2 tubing and the newly carbon rich water is diffused through your spray bar.

Hang on back filter – this is an easy one and certainly a favorite of mine. Just run the CO2 tubing up through the bottom of the intake valve of your hang on back filter. The filter will suck the bubbles up, break them up into smaller bubbles (aiding in diffusion) and then filter and release the water back into the tank.

Power Head – the power head diffusion method is very similar to the Hang on back method. Just run some CO2 tubing into the power head and the impeller blades will break up the bubbles and push them into the tank.

Airstones and Ceramic Diffusers – these work by splitting the large bubbles in the hose into much smaller bubbles. These get the job done, but not better than the other options available. This method doesn’t offer the bubbles enough time to diffuse properly.

U.P. Aqua CO2 Inline Atomizer for Aquarium


Check out the U.P. Aqua Inline CO2 Atomizer



  • A new or used CO2 safe tank is necessary. (5lbs is good for beginners)
  • Call your local CO2 suppliers to get your tank filled. (See how above)
  • Regulate your CO2 output with a regulator, solenoid, timer and bubble counter.
  • Purchase some CO2 Proof Tubing.
  • Diffuse your CO2 using one of the methods explained above.
  • Total cost: $150-$200


To learn how to install all of your components see the Tutorial coming soon.

Hi I'm Ryan, the owner of Aquathusiast. I've been keeping fish and aquatic plants for several years now. Along the way I've learned a lot. My goal is to take that knowledge and experience and help you, my readers, create the best aquariums and aquascapes possible. Drop us a line at or join us in the forums for a free aquarium consultation.
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