CO2...

by **Pleccy** on Sat Nov 07, 2009 12:12 am

CO2 (carbon dioxide) is important for all plants, it is a major ingredient for the process known as photosynthesis. Aquatic plants are no exception, and adding CO2 can be highly beneficial when used properly. However before you rush out to buy anything, first make sure that you actually need to inject CO2.

Do I need CO2?

In general my answer would be no, however that would apply if you have a low-tech system running on very basic equipment. CO2 is a limiting factor on photosynthesis and whether to inject it or not will depend on your lighting.

The greater the amount of light used on an aquarium, the faster the plants will photosynthesise. In spite of this the rate of photosynthesis will 'level off' if additional CO2 is not available, as any dissolved traces of carbon dioxide will be used up by the plants. Unless you inject more CO2, the plants may wilt and die.

Pressurised CO2- This is the most efficient and is the best choice for high-tec planted aquaria with high levels of lighting. It is also very reliable and also the most expensive. You can buy kits from aquatic stores or you can put your own together using a CO2 fire extinguisher and the relevant accessories.

Yeast-based CO2- A very cheap option and is safer than using a pressurised system, although they can be unreliable and aren't really ideal for plants that demand high levels of CO2, although they are fine for low-mid tech systems. They work by fermenting yeast to produce the CO2, and there are many kits on the market that come with their own mixtures, or you can make your own by using a plastic drinks bottle and some CO2 proof tubing. The mixture consists of yeast, sugar, bicarbonate of soda and water.

Liquid based CO2- This has seen a rise in popularity over the past year or two and one of the best products is Easylife Easycarbo, which is available in 250, 500 and 1000ml bottles. This product represents excellent value for money and I've been using it in my planted tank over the past few months with great success. Other excellent products include Seachem flourish Excel.

Words of warning- CO2 can be very dangerous, not only to fish but also to people and pets. Pressurized systems are the most dangerous, as a pressurized cylinder will go off like a rocket engine if it leaks. It is important that all equipment (including selenoids and pressure guages) is kept out of reach of young children and pets.