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Working Out My Co2 Ppm

Discussion in 'Lighting, CO2, Ferts & Flow' started by Nosnibor, Jul 22, 2007.

  1. Nosnibor

    Nosnibor Member

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    Hi All,

    I can't seem to get the search working to see if there are any posts already out there about this but, how do I work out my CO2 level in ppm?

    I have a drop checker so I suppose that will give me a constant sight check, but if I wanted to work out the ppm can someone tell me how to do it please - or point me to the post where the answer is.

    Thank you

    Martin :good:
     
  2. xxBarneyxx

    xxBarneyxx Member

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  3. Nosnibor

    Nosnibor Member

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  4. xxBarneyxx

    xxBarneyxx Member

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    Yeah just use a KH and PH test kit.

    CO2, PH and KH are linked.
    Increasing the CO2 will lower the PH and KH. By using the PH and KH measurements you can work out the CO2.
    The problem is that things like PH up/PH Down which chemically alter the PH does not add any CO2.

    For example.

    Tank without any buffering effects has a PH is 7 and KH is 10 you get 30ppm CO2

    Same tank with "PH Down" in to drop the PH to 6.8 with the KH at 10 still will give you a reading of 47.45ppm CO2. However the PH has not changed due to CO2 content but has been done with a "buffering" chemical so the CO2 level is actually still 30ppm.

    So If you have something like ADA Power soil which lowers your PH and Hardness this can throw the calculator out.

    By the same token this is why using tank water in drop checkers does not give an accurate rating. The best thing to use in drop checkers is known as 4dKH solution. This is used in the drop checker and because it has a known KH of 4 the only thing that is going to effect the results is the disolved CO2.

    To give you an idea of the difference. When I use tank water in my drop checker and put the indicator in it goes a greeny/blue colour which indicates around 12ppm CO2 (My ADA soil lowers my PH and KH which throws the results out). When I use 4dKH solution and add the indicator I get a dark blue colour which indicates 0ppm CO2.
     
  5. Nosnibor

    Nosnibor Member

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    EXCELLENT - That really explains it well THANK YOU.

    I use 4dKH in my drop checker due to some great advice from Supercoley1, so I can see that I have dark green colour, I have it around 2bps now as 1 was too blue. So would I be right in saying that it would be around 15-20ppm then? I will order a KH test kit on my next order as I only have pH low and pH wide.

    Martin :good:
     
  6. xxBarneyxx

    xxBarneyxx Member

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    Yeah if it is a dark green then it is probably in the 15-20ppm area. You will probably notice that overnight it will get lighter green/yellow then during the day will get darker.
     
  7. Nosnibor

    Nosnibor Member

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    That makes sense, thanks.

    I have a solenoid that cuts the CO2 two hours before lights out (as advised), so hopefully it is a good balance.

    I have a thread going regarding lighting which I hope to get some good advice from to choose the correct tubes for my aquarium.
    Cheers

    Martin :good:
     

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