need help to understand CO2 better

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cpm6t

Gambusia
MFK Member
Nov 8, 2011
577
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18
Sri Lanka
I've read posts here regarding CO2 requirements in aquarium and have few questions. Appreciate if I can get some input.

1.When there is surface agitation or air bubbling, O2 is said to get dissolved in water. But surface agitation is not recommended for to preserve the CO2 in water. What is the difference? When we bubble air through water doesn't CO2 get dissolved in water, same as O2?

2. Fish add CO2 to water through their breathing, is that correct?

3. From what I read in this forum, water changes is a source of CO2 in to water? How? If the tap water gets CO2 from air the tank water which is exposed to air should get the same amount of CO2, isn't it?

4. The aquarium (without a hood) is similar to an outside natural pond regarding CO2 supply (both are just open to the atmosphere). So why would an aquarium need CO2 injection and a natural pond does not?

I have a 220g tank with plants. I understand the CO2 requirement of plants and want to maximize its availability to plants without CO2 injection.
 
Hello; I have been reading threads about CO2 injection with the idea to perhaps try it someday. Allow me to say that as someone who has never used it, I have grown many nice plants without it.
On your first question, the threads I read suggest that injected CO2 levels can be kept at higher concentrations that would naturally occur in water if the surface aggitation of water is prevented. It seems to be felt that an undisturbed surface film will better contain the additional CO2 gas. Try some searches as there have been several threads on this particular portion of the topic.
Your second statement seems correct to me and I will add that plants undergo cellular respiration and can add CO2 to the water especially during the dark phase of a photopheriod.
I do not have any useful comment on the third question. I would like to get more information on that concept myself.
With regard to the fourth comment, that is the way that I see things myself. Both should have similar oxygen and CO2 levels due to partial pressures of the respective gasses in the atmosphere. There should be short term variations that are dependent on the populations of animals, plants and the amount of decaying material. These variations should somewhat stabalize over time as gasses will enter and leave the water.

My understanding so far is that CO2 injection is not precisely nesessary to grow plants but does enhance plant growth. One caution that grabbed my attention is that the homemade CO2 generators have been known to add toxins to water when not properly operated.
We should be getting some additional CO2 in our tanks from the fact that the levels of the gas are increasing in the atmosphere.
Many members swear by CO2 injection.
 
I need to get this tank densely planted in the long term. I'll trial which plants grow best in my tank setup. So far Cabomba and the other plant shown in my first picture (anybody know what it is?) seem to be doing above average in the tank. I want to maximize the CO2 availability without CO2 bubbling.
 
love that wood in that tank man. you have a lot of easy low growing plants. with co2 you can grow anything..fast and healthy. if u want to know all about plants and co2. sign up or go over to plantedtank.net. there u will find everything about plants/lights/co2/fertz etc on planted tank. u wont get much help on here. goodluck
 
This is the concept. Plants grow faster with higher levels of co2 Than that naturally occurring in the atmosphere. So if you want to grow plants fast, then add co2. Now, to keep co2 in the water, do not agitate the surface, because it will release the co2 into the atmosphere. Now, both o2 and co2 can occupy the water in good healthy quantity. The trick is to add o2 and co2 without agitating the surface of the water. What I do is to infuse both within the stream if the filtering process. So, if you have both your intake and exhaust from your filtering method well below the surface of the water, you will not agitate the surface. What I do is allow the water being filtered to run through my canister filter, then the output gets pumped above my aquarium into a cabinet which has my algae scrubber in it, which by it's open air process adds 02 to the filtered water, then it gravity drains into my co2 infuser that I made out of an old beer bottle, into the aquarium, so that the last thing that happens to my filtered water is a dose of co2 before it goes back into the aquarium, so that the new added water has both o2 to support my fish, and co2 to speed up the plant growing process. If you do not want to add co2 to your tank, then just aerate the heck out of your water to maximize the co2 exchange that will occur with the co2 found naturally in the atmosphere.
 
yep, i kept and over grown planted tank once with just a bubbler.

you will want to add co2 if you want to accelerate plant growth.
 
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