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Best and simplest way to inject CO2?

Fully agree foxfish,I think planted tanks get away with it because most of the bacteria is probably heterotrophic in the canister filter even without c02.heterotrophic bacteria are generally considered to be organic sludge degraders. They are mostly from the genera Bacillus and Pseudomonas. Most of these are facultative anaerobes; meaning they can function with or without oxygen. They will do completely different functions depending on the level of dissolved oxygen present.
 
I think it was Clive who explained why it wouldn't affect bacteria in the filter. I'll ask him if he still has the link to that topic.

Cheers
Gilles
Thanks i'd like to read this..
 
CO2 and oxygen can exist in the water independent of the other. Adding CO2 does not expel oxygen. Fish & bacteria carry on breathing O2, the presence of CO2 (in acceptable amounts) does not affect them .

CO2 is toxic in air eg in a pub cellar as it excludes the oxygen, so you asphyxiate due to lack of oxygen not excess CO2.

Fish suffer with high levels of CO2 in the water, even if the water is saturated with oxygen, due to the CO2 coming out of solution in their gills, thus excluding the oxygen.
 
CO2 and oxygen can exist in the water independent of the other. Adding CO2 does not expel oxygen. Fish & bacteria carry on breathing O2, the presence of CO2 (in acceptable amounts) does not affect them .

CO2 is toxic in air eg in a pub cellar as it excludes the oxygen, so you asphyxiate due to lack of oxygen not excess CO2.

Fish suffer with high levels of CO2 in the water, even if the water is saturated with oxygen, due to the CO2 coming out of solution in their gills, thus excluding the oxygen.
yes in acceptable amounts but if your flooding a canister filter with C02 which has already limited oxygen then surely the nitrifying bacteria suffer,even more than the fish.especially the last few hours before the lights come on in the morning...
 
yes in acceptable amounts but if your flooding a canister filter with C02 which has already limited oxygen then surely the nitrifying bacteria suffer,even more than the fish.especially the last few hours before the lights come on in the morning...
The oxygen won't be limited, adding CO2 does not alter the amount of oxygen in the water.

I would be more worried about the CO2 attacking the rubber filter seals. CO2 dissolves in rubber, making it either soft or hard, depending on rubber type. This is why the fire extinguisher uses a Teflon sealing washer and you have to use special CO2 piping.
 
C02 will kill anything that needs oxygen to survive....It would probably be the same as if your filter was to starting to track, as it starts to clog if it doesnt get cleaned regular.reducing the flow of oxygen to the nitrosonomas and nitrobacter..your biological filter need 4.3mg of oxygen to convert 1mg of toxic ammonia into nitrate..
This is a gross oversimplification of a complicated physiological process.
Firstly, the assumption that dissolved CO2 in the water column somehow affects the dissolved Oxygen content of the water is inaccurate. Do a search on gas Partial Pressure. The solution of any gas has nothing to do with the availability of any other gas dissolved in the same water.

Secondly, many of the nitrifying bacteria, such as nitrosomonas, are actually chemotrophic autotrophs, which means that they are able to fix Carbon in exactly the same way that plants do by uptaking CO2 and then using the CO2 in a Calvin Cycle procedure which fabricates glucose. Other micro-organisms in the tank and filter are chemotrophic heterotrophs, which means they are unable to fix Carbon from inorganic CO2, so they get their Carbon from organic carbohydrates which are the pollutants in the tank, and which are also produced and exported by the fish and plants. There are a wide variety of germs in the tank water, in the sediment and in the filter. They are not affected by CO2 in the way that fauna are affected. The toxic mechanism of CO2, called hypercapnia, is a function of the way in which higher organisms collects Oxygen, primarily, but not limited to the function of the hemoglobin (or hemocyanin in some inverts). CO2, through it's action of lowering the blood pH, interferes with the process by which these Oxygen carrying proteins bind the Oxygen, and so lowers the Oxygen carrying ability of the blood. Bacteria and archaea do not use this mechanism and are therefore immune to that particular debilitating effect. Check the video links in the thread not enough oxygen... | UK Aquatic Plant Society

Thirdly, CO2 dissolved in the water column and then sucked into the filter is exactly the same as pumping CO2 into the filter. Does anyone imagine that 30ppm dissolved CO2 in the tank water somehow falls to zero when that water enters the filter, and then somehow 30ppm reappears after the water exits the filter? Whatever concentration of any gas in the tank is also in the filter.


O2 is definitely the limiting factor inside a canister filter & I simple dont believe the whole canister concept to be very biologically efficient full stop.
What about the Oxygen added to the water column by plants during the photoperiod? Doesn't the gas find it's way into the filter as well as into the sediment? Naturally, at night, when there is no added Oxygen, it would be better to have aeration such as with a sump or with a wet/dry.

From my perspective it just seems like a bad practice to pump C02 into your biological filter but .... it does seem to work for a lot of people!
And once we understand why it works, what the limitations are, as well as what the benefits are then we can proceed to modify the perspective.

Cheers,
 
Thanks for the detailed explanation Ceg..
With the C02 reducing the pH of the water doesnt this lower the efficiancy of the bacteria as a pH lower than 6.7 can significantly reduce productivity.I understand optimum is between 7.2 and 8..Is it also true theres many types of bacteria that convert ammonia but only a few that convert nitrites....

Thanks
 
Thirdly, CO2 dissolved in the water column and then sucked into the filter is exactly the same as pumping CO2 into the filter. Does anyone imagine that 30ppm dissolved CO2 in the tank water somehow falls to zero when that water enters the filter, and then somehow 30ppm reappears after the water exits the filter? Whatever concentration of any gas in the tank is also in the filter.
Reading this post with interest but on the above point, I can see how the co2 levels would be the same inside the canister as in the rest of the tank with it being in equilibrium. Would direct exposure to pure co2 in the case of trapped pockets have a negative impact on the bacteria. I guess this would be minimal though considering the small surface area exposed.
 
I Suppose it depends on how clean the filter...

Ceg ..At the point of entry of the co2 surely must be higher that 30ppm until it equalizes in the tank...so if the co2 is injected into the filter this would be its highest point of C02 saturation..
 
If there are trapped bubbles in the filter then that means the CO2 is not dissolved. In fact that's one of the major problems of any diffuser. The rate of solubility of the gas into the water is not as fast as the injection rate. That's why the burping of the filter. At the point of entry, if the CO2 concentration is higher, then more CO2 loving bacteria will develop at that location than at other locations in the filter. At lower pH the NH3<->NH4+ equilibrium shifts to the right, so there is lower concentration of toxic NH3. In any case, the plants, if healthy will uptake NH3/NH4+ so it doesn't really matter that some bacteria are less effective at lower pH. If there is a higher Oxygen due to plants as well as higher CO2 and nutrient content then there is also a higher bacterial population. Bacteria need PO4, Potassium and Iron as well, and all these things are supplied in abundance when we dose the water column. Bacteria are not the only denizens of the filter. Archaea are another life form that do probably most of the work in the Carbon Cycle as well as in the Nitrogen cycle.

Cheers,
 
All this suggest to me that if you are using a canister filter for the manufactures designed purpose then concentrating high levels of co2 within the vessel is not a good idea!
I find it hard to believe that the changing conditions inside the filter throughout the day & night, the build up of gas & ph swings are the best environment for consistent & healthy bacteria growth.
Like I have already stated ... This might not actually matter that much but is seems to me you are effectively converting a biological power filter into a co2 reactor - not nurturing the ideal biological environment?
 
Theres certainly alot going on inside the canister filter,which to me seems like the balance could be upset very easily...until i can understand the workings properly i think i will stick to my sump with aggressive aeration and use more co2 after the biological side...
I think someone like Ceg should start a thread called understanding the working of a co2 injected canister filter and what kind of bacteria does what...lol...
 
Hi all,
I find it hard to believe that the changing conditions inside the filter throughout the day & night, the build up of gas & ph swings are the best environment for consistent & healthy bacteria growth.
Secondly, many of the nitrifying bacteria, such as nitrosomonas, are actually chemotrophic autotrophs, which means that they are able to fix Carbon in exactly the same way that plants do by uptaking CO2 and then using the CO2 in a Calvin Cycle procedure which fabricates glucose. Other micro-organisms in the tank and filter are chemotrophic heterotrophs, which means they are unable to fix Carbon from inorganic CO2, so they get their Carbon from organic carbohydrates which are the pollutants in the tank, and which are also produced and exported by the fish and plants. There are a wide variety of germs in the tank water, the sediment and the filter.
Like Clive says, it doesn't matter as much as you might imagine. This is really because the micro-organisms that decompose organic products are a complex assemblage of species that have evolved over billions of years.

We used to have one of these in the lab. <Winogradsky column - Wikipedia, the free encyclopedia>.

If a scarce product like fixed nitrogen (NH3, NO2 etc) is available in any environment, organisms will have evolved to exploit it. Low pH, high levels of CO2 and low levels of oxygen are very common in environments where decomposition is occurring, principally because the bacteria are utilising oxygen (O2) and producing CO2.

The difference is in the end product produced (e.g. CO2 if aerobic decomposition of organic matter is occurring or H2S if anaerobic), and in the efficiency of the process. In our terms biological filtration is all about oxygen, as long as we have enough oxygen everything else is much less important.

A lot of the problems people attribute to low pH etc are really to do with low levels of dissolved oxygen (it is the O- in OH- that is the base) leading to a failure in biological filtration.

Fish bits
The practical ramifications of this were why I wrote: "Aeration and dissolved oxygen in the aquarium": <plecoplanet: Aeration and dissolved oxygen in the aquarium>.

Some might also be interested in this page on fish physiology and the Bohr-Root effect: < Fish Respiration>.

cheers Darrel
 
Hi all,


Like Clive says, it doesn't matter as much as you might imagine. This is really because the micro-organisms that decompose organic products are a complex assemblage of species that have evolved over billions of years.

We used to have one of these in the lab. <Winogradsky column - Wikipedia, the free encyclopedia>.

If a scarce product like fixed nitrogen (NH3, NO2 etc) is available in any environment, organisms will have evolved to exploit it. Low pH, high levels of CO2 and low levels of oxygen are very common in environments where decomposition is occurring, principally because the bacteria are utilising oxygen (O2) and producing CO2.

The difference is in the end product produced (e.g. CO2 if aerobic decomposition of organic matter is occurring or H2S if anaerobic), and in the efficiency of the process. In our terms biological filtration is all about oxygen, as long as we have enough oxygen everything else is much less important.

A lot of the problems people attribute to low pH etc are really to do with low levels of dissolved oxygen (it is the O- in OH- that is the base) leading to a failure in biological filtration.

Fish bits
The practical ramifications of this were why I wrote: "Aeration and dissolved oxygen in the aquarium": <plecoplanet: Aeration and dissolved oxygen in the aquarium>.

Some might also be interested in this page on fish physiology and the Bohr-Root effect: < Fish Respiration>.

cheers Darrel

Just read your artical Darrel"Aeration and dissolved oxygen in the aquarium":,well impressed with the detail you included.
Thanks excellent read.
 
I still believe the best thing is not to have any build up in your filter,a build up will contain alsorts of nasty bacteria,excellarating any illness your fish have,making a minor problem a major..but obviously a plant only tank makes this irrelavent...
 
Hi all,
Thanks excellent read.
Thanks for reading.
I still believe the best thing is not to have any build up in your filter,a build up will contain alsorts of nasty bacteria,excellarating any illness your fish have,making a minor problem a major..but obviously a plant only tank makes this irrelavent...
You definitely don't want a build up of CO2 in the filter, but I'm not sure that it will have any major microbiological effects.

The advantage of planted tanks is a lot to do with the net oxygen increase. Adding CO2 is a slightly different issue. I don't use CO2, this is because:
  • I'm not particularly interested in fast plant growth.
  • I'm pretty tight with my money.
  • but principally I don't want to accidentally asphyxiate my fish.
In a tank without any livestock it would be slightly different.

cheers Darrel
 
All this suggest to me that if you are using a canister filter for the manufactures designed purpose then concentrating high levels of co2 within the vessel is not a good idea!
I find it hard to believe that the changing conditions inside the filter throughout the day & night, the build up of gas & ph swings are the best environment for consistent & healthy bacteria growth.
Like I have already stated ... This might not actually matter that much but is seems to me you are effectively converting a biological power filter into a co2 reactor - not nurturing the ideal biological environment?
The idea of nurturing the ideal biological environment is little bit of tunnel vision and maybe many sump lovers subscribe to this. I think it's better to view the tank as a system upon which the bacterial load is a foundation. The foundation needs to be strong enough to support the rest of the system but it doesn't have to be so strong to the exclusion of all other components. There is a lot of leeway. In a brand new tank the development of the bacterial load is critical to success because the population and diversity is weak. So we do as much as we can to get it strong. Once it's up and running then the bacterial load is versatile and flexible. As Darrel mentions, there are more than one species doing similar jobs so we really don't need to worry too much unless we are adding chemicals that specifically destroy bacteria. CO2 is NOT one of these destructive chemicals.

Also, it's probably another fantasy that manufacturers know any more about microbiology than we do. Filter manufacturers know a lot about building plastic buckets and attaching pumps to those buckets. That's about it. Some manufacturers of aquatic products don't even know the first thing about the science of the product that they build. They are simply businessmen who see and fill a market niche. How long ago was it that DC vendors included instructions to use tank water to fill the DC? A totally inappropriate instruction, rendering an already poor tool even more pathetic. WE are the ones who figured out how to use the DC in a way NOT sanctioned by the manufacturer, and which, it turns out works 100% better than "manufactures designed purpose". These manufacturers are the same bozos who remove the media from the bucket when doing the flow rate tests to artificially enhance their official flow throughput ratings. WE are the ones that had to come up with a better formula for figuring out what filter rating to use to give ourselves a better chance of success in a CO2 injected tank.

So doubling up the use of a canister filter to act as both filter and CO2 diffuser does no harm to the microbes and can yield a much better rate of success than using an in tank diffuser, ESPECIALLY if the tank size is large. I mean, look at this recent example=> Low-light, Hi-tech planted tank | UK Aquatic Plant Society

A 500L tank using the filter as a diffuser. How healthy is that system? Please people, can we get rational about this? How we feel about some process or procedure should be evaluated within the context of facts and data. Feelings do not necessarily equate to reality. Feelings without supportive data is the reason we get into trouble.

Cheers,
 
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