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Understanding CO2 & Set-up Guide 


Understanding CO2 in Planted Aquariums

CO2 is arguably the most important element in the planted aquarium. It is required for respiration and growth by all aquatic plants, used in a process called photosynthesis. Plants require a constant supply of CO2 during the light hours, otherwise they can suffer. They combine the CO2 with water and light energy to produce oxygen and sugars to enable growth.

In the wild, plants get their CO2 in large quantities naturally from substrate (mud) and degrading plants. However, in a enclosed aquarium, CO2 is very limited. Water from your tap is depleted from CO2 and plant decay in an aquarium is minimal compared to the wild. This is why many aquarists have found out that supplementing CO2 really does help their plants grow much better and a lot stronger.

Deciding whether you need CO2 injection or not, or how much you need, depends on the amount of light you are supplying, and the selection of plants you wish to grow. However, for a more successful planted aquarium, we always recommend injecting CO2.

In low light aquariums, CO2 is not always necessary. Plants are less stimulated to grow under low light,  so extra injected CO2 is not required as there is normally enough CO2 supply coming from surface agitation, fish respiration and organic breakdown of dead plant matter. However, adding CO2 in a low light tank will still improve the quality of growth and health of your plants.

In aquariums with medium to high lighting, CO2 injection becomes vital. With more light available to the plants, the quicker they grow. This results in a higher demand for CO2 by the plants. Under medium to high lighting the aquarium becomes CO2 limited. The aquarist must now start adding CO2 to meet the plants demands. If the aquarium remains CO2 limited, your plants will suffer from growth deficiencies, and as a result you will experience algae formations.

What you need to get started with CO2 injection:


Putting it all together:

Putting your CO2 equipment together is simple, once you know how! By following the diagram below you will have your CO2 system up and running in no time. 

Use a spanner to tighten the regulator to the CO2 bottle. Then attach all other compents together as displayed above. Once everything is connected together, open the needle valve slightly on your regulator before releasing the gas from the bottle. This will avoid damage to the solenoid when you first open the main valve on your bottle. Next, switch on the main valve on the bottle to release the CO2. The left gauge on the regulator should move to around 800-1000psi if the bottle is full.

To release the CO2 from your regulator, slowly turn the needle valve about half a turn and wait for the CO2 bubbles to be seen through your bubble counter. Using the needle valve again, aim for around 1-2 bubbles per second coming through your bubble counter (a higher rate may be required in larger aquariums). The needle valve is quite sensitive, so only small movements are needed to alter the rate of CO2. Over the next couple of hours monitor your CO2 levels using your drop checker. Adjust as necessary until your drop chcker fluid has changed to green. Remember, it takes around 1 hour for the drop checker to respond to levels of CO2. So when you look at your drop checker, it will be indicating the level as of 1 hour ago.

The solenoid can be set using a Electric plug timer to turn the CO2 off at night. Electric plug timers are available from any DIY store and most supermarkets. The solenoid valve will open when swicthed on, and close when switched off.


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