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CO2 measurement

Discussion in 'CO2 Enrichment' started by Tom Barr, Sep 16, 2010.

  1. Tom Barr

    Tom Barr Founder
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    CO2 is perhaps one of the most controversial and problematic parameters for planted aquarist. Is enrichment natural? Why add it if I've seen other tanks that do not use it still look nice and grow plants still?

    These are often folks that have not used it that ask such questions, but these questions are valid and fair.

    Can you think of systems where CO2 at say 10-40ppm is natural and stable?
    How would you measure it and also verify those levels using a known reference?
    We do this for nutrients and for light, but what about CO2?



    Regards,
    Tom Barr
     
  2. scottward

    scottward Guru Class Expert

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    Longevity of CO2 supply?

    Tom, those thanks that don't supplement CO2 (i.e. via CO2 cylinder, regulator etc), still need a CO2 source from somewhere don't they...and this CO2 source, in these cases, is coming from a specially composed substrate that slowly breaks down producing enough stable CO2 to support growth?

    Needless to say, these tanks that don't supplement CO2, would have to be very low light - with higher lighting levels this kind of result would be impossible without CO2 supplementation, correct?

    These non-supplemented tanks that look great are going to be fairly short lived aren't they? Eventually, whatever is supplying the carbon source (CO2 from substrate?), is going to run out.

    This excludes using, Excel etc, of course.
     
  3. Ekrindul

    Ekrindul Guru Class Expert

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    CO2 enrichment allows us a great deal more design freedom, or at least a more immediate level of control over design. "El natural" isn't very forgiving of indecisive design. You can't go changing things everytime you see a better way and maintain a stable environment. In some ways, and to some people, that may be too confining; others may see it as more challenging. You have to be confident of your initial design, put more forethought into it. Replace some of your freedom with patience. The maintenance end of CO2 maybe more work, but it allows you a great deal of control.

    How many natural bodies of water that support life escape evaporation/rainfall/current, moving from one place to another. Water in nature is constantly being filtered and renewed.
     
  4. scottward

    scottward Guru Class Expert

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    I don't think CO2 enrichment is very forgiving of indecisive design either! ;-)
     
  5. dutchy

    dutchy Plant Guru Team
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    I'm not sure a direct comparison between natural systems and a tank can be made. There are not many natural streams that have high CO2. Most are very low and filled with algae, which seems logic. Aquatic plants in those streams are mostly coverd with algae too, except for the top few inches.

    We can prevent this by adding CO2. Still CO2 is a very difficult matter. There's not much too rely on. pH/KH table, drop checker, pearling, all not more then indicative. Fish? Well, we can watch the fish, but if I need 120 mg/l of CO2 to make the fish surface, (See Yme's topic) that's too much too. I don't want 120 mg/l, I want a stable 40 mg/l. I really ask myself if these levels like more than 100 mg/l are not damaging fish health. Not directly, but inderictly in relation to size and longeviness.

    Better watch plants, take CO2 slowly back until you get some problems, like BBA or stunting or if you start with BBA to begin with, gradually increasing until the side effects are ellaviated. This takes weeks of course, not a few days like using fish.

    I wish there was a reliable way too measure CO2 for the hobbyist, without investing in a $$$ CO2 meter. With light I can use my PAR meter and a somewhat useful graph can be made that most people can use, nutrients is easy too, I just add more than the tank needs.

    But CO2? I have good growth, and no algae except when I make mistakes myself. Still I'm in the dark. Do I have 30 ppm, 40 ppm or 80 ppm? I don't want 80. Or maybe it's just human nature to calculate everything and we have too learn too look at our plants.

    It's possible. Look at the picture of the Stellata.
    [​IMG]
    Beautiful plant which was over 9 inch wide. But look at the section in the middle. You can see that it's smaller than the lower and upper part of the plant.

    The period in which the plant grew smaller coincided with a period of higher water temperature. With higher water temperature CO2 demand rises. Apparently the plant got somewhat limited and grew smaller leaves for sometime. I didn't get algae in this period. When temperatures dropped, it grew back to it's original size.

    This tells me that I have a good CO2 level, but only for the water temperature I'm using. So I'm kind of at the lower limit. So using plants as a test works, but we have to be able to explain why things happen.
    That's not easy for a lot of people. Watching your plants carefully on a daily basis helps.
     
    #5 dutchy, Sep 17, 2010
    Last edited by a moderator: Sep 17, 2010
  6. 1077

    1077 Guru Class Expert

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    Do not fish produce some CO2 and waste ,that is being broken down and used by plants along with possibly added ferts?
     
  7. 1077

    1077 Guru Class Expert

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    I guess what I am trying to say is that fish produce some CO2, and waste from foods offered being broken down continuously ,would also contribute to CO2 levels in non CO2 injected set ups.
    So long as plant and fish load remained relatively stable I cannot see CO2 being depleted albeit present at low level.
    I will happily await thoughts on this as low tech,low light, low CO2 is currently what I am training my efforts on.
     
  8. fjf888

    fjf888 Guru Class Expert

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    You are correct. From what I have learned plants like a constant level of CO2. So as long as your parameters stay the relatively same in the tank, bioload, light, amount you feed, etc you should be able to maintain a natural setup for awhile. If you follow the setup that Tom lays out, you can use leonardite or peat to provide a slow release breakdown of carbon that your plants can utilize. As the fish produce waste this will help enhance the substrate and also aid in further decomposition which will produce some CO2.

    I have a tank that has been running for 3 years setup exactly like the walstad suggests in her book. Its a 6 gallon with 10 espei rasboras and some amano shrimp. After about a year plants started to stunt, but they came back much better when I started using small amounts of dry ferts. I'm not sure what the life is for these tanks, but presumably it should be a long time if balance is achieved. Getting to that point takes a good plan and to be willing adjust at signs of trouble before things get bad. For instance, I would change my water all the time, because I was paranoid, within days I would have a new algae outbreak. When I stopped doing this the algae was greatly reduced. You should do fine in your setup. If I had it to do over again. I probably would have setup my first tank as a low light no CO2 tank, rather then dive right into the CO2. I incorrectly assumed you needed CO2 and super bright lights to grow plants. Now I know better.

    Plus you eliminate the wonder that we all experience like laid out in this thread. How much CO2 am I really adding? What is the long term effect on fish related to elevated CO2 levels? Am I dissolving CO2 efficiently and effectively, although you do miss out on all the practical plumbing experience. :)
     
    #8 fjf888, Sep 17, 2010
    Last edited by a moderator: Sep 17, 2010
  9. fjf888

    fjf888 Guru Class Expert

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    somehow i posted a message 2x
     
    #9 fjf888, Sep 17, 2010
    Last edited by a moderator: Sep 17, 2010
  10. 1077

    1077 Guru Class Expert

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    Thanks Fred,

    I think it shall be some time before I feel comfortable with the Gas, But I am reading,learning,and observing.
    Dry fertz came today!
     
  11. dbazuin

    dbazuin Guru Class Expert

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    Tom can you tell us what the temperature was in both periods?
     
  12. dutchy

    dutchy Plant Guru Team
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    Well, I'm not Tom, but I suppose you mean me... I take that as a compliment ;)

    Normal temperature is 27 Celsius (81F) and elevated temperature was 32 Celsius (90F)

    regards,
    dutchy
     
  13. dbazuin

    dbazuin Guru Class Expert

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    You can sure do that :)

    Is 27 celsius your normal temp?
    Mine is between 25,5 and 26.
    So I am guess that I am fine with my 40 mg/l CO2.
     
  14. dutchy

    dutchy Plant Guru Team
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    Yes, 27C is my normal temperature because I keep discusfish.

    Concluding just based on numbers you should be ok with 40 mg/l of CO2. You could use some more flow, up to 10x the tank volume. If you put your Eheim in manual mode and then push the + key a few times it will give you more flow. The only disadvantage is that the optional electronic gadgets don't work anymore. The factory setting of these filters is just 700 lph. But in manual mode, you can get 1100 lph. That's a lot more.

    regards,
    dutchy
     
  15. dbazuin

    dbazuin Guru Class Expert

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    Are you sure?
    That is a big diffrence.

    Not that I have any problems with it right now.
    I can see leaves move every where, at least where the can move. The Pogostemon Helferi is not very flexible :)

    A other thing is cleaning the tubes. That makes a big difference.

    Every thing is doing fine. We only need to rearrange the plants a bit to get a better looking scape.
    That is where we are working on right now.
     
    #15 dbazuin, Sep 18, 2010
    Last edited by a moderator: Sep 18, 2010
  16. dutchy

    dutchy Plant Guru Team
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    Yes, I'm sure. I have 2078e's which are the same. I tested and measured.

    regards,
    dutchy
     
  17. Wet

    Wet Lifetime Members
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    So, um, I have a habit of throwing out the fine manuals after my stuff is working. What's manual mode on the Eheims? Adjusting it as if to prime?

    Thanks!
     
  18. scottward

    scottward Guru Class Expert

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    Another thought that I had (sorry for breaking the Eheim discussion above)...

    With the natural approach, I guess that there is a lot more competition between species for CO2, such that selection of plants is more critical to overall success. Whereas, by enriching with CO2, plant species that would normally 'beat each other up' over CO2 can be located side by side and still both grow fine.

    Dutchy - totally understand your comments about temperature - in Australia I get up into the 30 degrees in summer - I have to belt my tank with CO2 - and just keep watching the plants (no drop checkers etc).

    Also, regarding the means of measuring CO2, because the CO2 level varies from location to location in the tank, we'd almost have to have a well defined 'reference location' so that we are all comparing like for like when reporting our findings - that seems pretty impossible though?

    Scott.
     
  19. Whiskey

    Whiskey Subscriber

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    This is a very intresting thread - I will definitally be following along.
    One thing that comes to mind is the pics from your recent trip to Northern CA. Another is streams that are fead directly from underground.

    A good way to measure if CO2 is present would be to measure KH-PH of a sample, then let it sit overnight and repeat the measurement - this should prevent acids in the system from messing with readings - A drop checker with a 4DKH solution also will isolate the measurement from acidic interfearance but be far less accurate.

    How comon is it to see CO2 enriched systems in a natural setting? How much CO2 is in the typical envryomnet that many of the "Common" hobbiest speices come from?

    Whiskey
     
  20. dutchy

    dutchy Plant Guru Team
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