plant your tank
Retired Moderator ⚒️
- Oct 12, 2009
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- Lincoln uk
C02 Diffusion methods
This short article is to help make people aware of the different carbon dioxide diffusion methods in the planted aquarium. Firstly, a quick what is C02 and why diffuse?
There are a few things that are important to aquatic plants, these are water, light, carbon dioxide, nitrogen, phosphorus, potassium, trace elements and flow for dispersion around plants. Normally we would put them in this order as more light = the need for more C02, more nitrogen, phosphorus etc etc.
So what does C02 do?
Carbon dioxide is the main building block for aquatic plants, as the plant adsorbs the C02 it then turns the C02 in a simple sugar. Tanks with C02 injection normally grow quite vigorously. Some tanks with low light (below 1 wpg as a guide) can normally get away without C02 injection.
Why is correct diffusion important?
It is said that one of the first people to use C02 in an aquarium was Takashi Amano, and it was him who strived to make the best diffusion methods. The way to ensure the C02 is being correctly diffused around the aquarium is to use a drop checker, have a read here about drop checkers and how they work. It is important to diffuse C02 correctly to ensure all plants get what they need to survive
Just a quick note...always observe your fish when diffusing C02, if your fish are gasping, then you need to switch the C02 off and either add an airstone or move your filter outlet up to the surface to give more agitation. A water change is also a good idea
What does correct diffusion look like on the plants?
In the world of aquascaping and planted tanks people seems to strive for the 'pearl'. This is when the plant is photosynthesising and producing small oxygen bubbles on the plant leaves (so the plant will breath in the C02 and breath out the 02). It looks like this...
So which diffuser?
There are many diffusers on the market, there are still some arguments surrounding methods of C02 diffusion and which is best...this is just a guide. These are the 4 most popular diffusion methods.
The glass diffuser
Probably the most commonly used diffuser. You can pick up glass diffusers relatively cheap, they remain popular because they work well by releasing small bubble of C02, these small bubble then penetrate the leaves during photosynthesis. It's important to place the glass diffuser in range of the flow in the tank, whether thats under the outflow or in it's path. The advantage of using these is that you can see where the C02 is being diffused. You can also using them for nearly all sizes of tank. They can be used with yeast based C02 as well, just be prepared to wait for the pressure to build up in the diffuser before you see bubbles. This can take anywhere from 2 hours to 2 days in my experience. The glass diffuser can and will get quite dirty, the best way to clean the diffuser is to soak it for a few hours in a weak bleach solution, then soak it in water containing dechlorinator for another couple of hours afterwards.
The Ladder diffuser
Used mainly with yeast based C02, due to the fact that not as much pressure is needed to start the diffusion. The ladder works by working small bubbles up the ladder style system and as the bubble of C02 works it's way up the ladder it disperses and C02 is worked into the water. They aren't really seen in aquascapes as the ladder systems normally get in the way and look somewhat ugly. As with the glass diffuser, it's important to use the ladder in the flow of the water, however, you cannot see where the bubble is being dissipated around the tank. It is best used with a drop checker to ensure you're getting adequate dispersion. The ladder also needs cleaning regularly to stop build up of scum, normally from yeast based C02.
The reactor (for external filter)
More popular with the USA market, this diffuser works by connecting your external filter to an inlet and outlet on the reactor, then the C02 is connected (only used with pressurised C02). The C02 is totally dissolved into the reactor and then blown out of the outlet on the filter. There is some argument whether this is the best way of diffusing C02, some say yes, some say no. There are some different ways reactors can be used, they can be DIY or used in sumps for larger tanks. The external filter reactor will slow the flow on the filter.
The Atomiser (in line and in tank)
The new kids on the block regarding C02 diffusion. Both work by producing very very small bubbles that diffuse into the water. The in line version connects to the filter outtake pipe and the C02 (pressurised) connects to the diffuser. The C02 is pushed through a ceramic plate, the plate being very compact to produce the small bubbles. The in tank works by the same process, but is attached the same way as the glass diffuser. Theses diffusers will only work with pressurised C02 and will work properly with a minimum of 2 Bar of pressure. In my experience they don't work as well with lower pressure. These products also need a bleach soak every once in a while. In my experience thses are excellent methods of diffion. The in line diffuser can make a hissing sound, just to make people aware, before they think they have a leak of C02
this is just a quick guide, if anyone has anything to add or comment, then please feel free.