What is a CO2 Diffuser? Types of Diffusers & How to Use Them

The CO2 diffuser is a part of your CO2 regulation system. The CO2 regulation system usually consists of a CO2 regulator, CO2 cylinder (the source of CO2), and the CO2 diffuser. The diffuser is an add-on or standalone device and its main purpose is to dissolve the CO2 from the regulator into the aquarium. The CO2 diffuser is attached to the tubing connected at the bubble counter, part of the CO2 regulator. When you buy tubing for CO2,use CO2 tubing that is harder, thicker and more durable than other tubing to avoid unwanted situations or accidents because of breakage or leaking. The other end of the CO2 tubing is connected to the diffuser for better CO2 utilization.  The CO2 diffuser breaks down the big bubbles from the bubble counter into tiny bubbles to be dissolved into the fish tank more easily and efficiently, raising the level of CO2 in the aquarium water. It is similar toan air diffuser exceptit diffuses CO2 into the water.

CO2 Diffusers

Types of CO2 Diffusers

The CO2 diffuser comes in many shapes, sizes, and materials. It can be made of plastic, glass, or it can be a standalone device such as a submersible powerhead or DIY (Do-It-Yourself) system. Almost all types of CO2 diffusers are submersible in the fish tank,except some types that dissolve the CO2 outside the aquarium and then insert the CO2 enriched water into the tank. There are many differences between the CO2 diffusers. Some are safer, cheaper,or more efficient than others.

One of the least efficient CO2 diffuser is the airstone diffuser and it should be avoided. The CO2 bubbles it creates are quite big (they should be as tiny as possible) and there is hardly any CO2 dissolved into the aquarium.

A very common one for small tanks is the ceramic glass CO2 diffuser that is submerged into the fish tank and secured to the aquarium glass with a suction cap. This one creates very fine bubbles and is relatively cheap.

The ladder CO2 diffuser is also used in smaller tanks and it is considered efficient and reasonably priced. It is shaped like a ladder, hence the name.

Another type is the in-line CO2 diffuser that connects to the fluvial canister filter and it is recommended for larger aquariums. In-line diffusers have a good reputation because they are considered safe and very effective.Due to the CO2 entering the water and having plenty of time to dissolve,you save on CO2 consumption.

The CO2 reactor is one of the most expensive diffusers and provides the highest output of CO2, but comes at a great price and it is used for really large aquariums.

Basically, the best type of CO2 diffuser is the one that makes micro bubbles, doesn’t leak,and is safe and secure. Most of the high-quality CO2 diffusers brands offer this. It is better to invest a few more dollars and be protected with a quality product,especially if you are not very familiar with CO2 regulation.

CO2 Diffusers

Setup and Use

The CO2 diffuser connects with the end of the CO2 tubing that is attached to the CO2 regulator at the bubble counter. When the CO2 diffuser is submerged into the fish tank, the CO2 inflow from the regulator will enter the fish tank raising the CO2 level of the aquarium water.

If the CO2 diffuser is an add-on to the CO2 regulator, it simply starts working right away when it is submerged into the fish tank and connected with the CO2 tubing. If it is some sort of pump or DIY electro-mechanic device, then it needs power to work.

Always Check the Water Parameters

The CO2 diffuser will do its part more or less efficiently, but it can change the water parameters in your fish tank. Always test your pH and KH parameters first.  Usually you would need less CO2 if you have few plants and soft and acidic water because of the carbonic acid;more CO2 is needed for hard or alkaline water and if you keep multiple plants. In addition, count the bubbles to be sure you are diffusing the proper amount of carbon dioxide into your aquarium.

1 thought on “What is a CO2 Diffuser? Types of Diffusers & How to Use Them”

  1. It is so cool to see that this tool can be used to make plants grow healthily. My brother was talking about getting a CO2 refill and I wonder if he is using it for this. If he is, I will let him know to always check the water parameters of it.


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