Carbon Dioxide CO2


Carbon dioxide is essential to plant growth. Carbon dioxide in its purest form is a gas, but like oxygen it can be readily disolved in water. Aquatic plants utilize this disolved carbon dioxide to photosynthesize in a similar way that grass or a tree in a garden would do. Diffusers use membranes or reactors to dissolve drops of gaseous CO2 directly into the aquarium water, artificially creating the perfect environment for aquascaping.

In the same way as garden plants, aquatic plants need lighting, fertilizers and CO2. These are essential factors governing the speed of growth and health. With the addition of modern T5 or LED lighting systems and liquid/substrate fertilizers aquariums can become unbalanced. CO2 is required by these plants to balance the aquarium otherwise algae can quickly take over the tank.

It is important to remember CO2 can cause PH swings in the aquarium as carbon dioxide when disolved in water is acidic. Problems often arise at night when the plants do not photosynthesize. The build up of CO2 being added to the aquarium causes the pH to drop rapidly and can be detrimental to aquatic life. Adding carbon dioxide to the planted aquarium needs to be closely monitored.

There are many different ways to deliver carbon dioxide in the planted aquarium. These avenues differ in price, difficulty, success and maitenance. Below is a list of commercially available routes and a brief overview of each.

Pressurized CO2


CO2 Liquids

CO2 tabs

Electronic CO2

Pressurised CO2 is the best option if it can be catered within budget. DIY CO2 is an excellent substitute for the budget conscious and will achieve similar results.