Co2 Injection / PH Swing

Discussion in 'Carbon Dioxide (CO2)' started by phantomfisher, 5 Nov 2009.

  1. phantomfisher

    phantomfisher Member

    Messages:
    56
    The Co2 content in my 400 litre tank is around 30ppm which gives a nice green reading on my drop checker (around 1.5 bubbles per sec). I have 4 x 54w T8’s on for 10 hours per day and start the Co2 2 hours before lights on and stop it 2 hours before lights out. The results of this is that before switching on the Co2 in the morning my PH has climbed to around 7.10 and by the time I switch the Co2 off the PH has dropped to around 6.80, is this an acceptable swing or do I need to do something about it? :?
     
  2. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    Hi,
    I suggest the following:

    Forget about pH swings and make sure that you avoid CO2 swings, because that's much more troublesome.

    Cheers,
     
  3. phantomfisher

    phantomfisher Member

    Messages:
    56
    I monitor my Co2 using a drop checker, when you say avoid Co2 swings is it acceptable to just keep the drop checker in the green all the time or is more accuracy required?
     
  4. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    No, you don't need to be accurate, you just need to be consistent. In fact the dropchecker really isn't all that accurate anyway. It just gives you a clue. Are you using 4dkH water in the dropchecker or are you using tank water? For further details review the article CO2 MEASUREMENT USING A DROP CHECKER in the Tutorial section. pH swings are irrelevant in the tank, however inconsistent or varying CO2 levels tends to trigger certain forms of algae, the most prominent of which is BBA. Because the CO2 turns on and off this will naturally be a rise and fall in the carbonic acid production which will be reflected in the pH. This is not a big deal as Carbonic is a weak acid. People do much more damage to their fish by adding strong toxic acids to the tank in order to control pH.

    Cheers,
     
  5. phantomfisher

    phantomfisher Member

    Messages:
    56
    I am using a Red Sea drop checker and the instructions say to use 1ml of aquarium water plus 2 drops of their indicator.

    I have only been using this drop checker for a couple of weeks but have not been using 4dkh water will this cause a problem?
     
  6. Superman

    Superman Member

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    1,804
    Location:
    Cheltenham
    Using 4dkh water will ensure that the colour changes from blue-green-yellow is at specific levels of pH to give you a green reading of 30ppm of co2.

    Using tank water will make the reading to be less accurate as things in the water will mean that the drop checker will not be green at 30ppm of co2.

    Therefore, it's a safer bet to use 4dkh water.
     
  7. phantomfisher

    phantomfisher Member

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    56
    You learn something every day, I will get some 4dkh and use from now on. :thumbup:
     
  8. roadmaster

    roadmaster Member

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    Why do so many warn against the use of pH up or down products if pH swings are not harmful to our fishies?
     
  9. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,953
    Location:
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    The answer is simple. The pH swings that occur naturally in the tank are irrelevant, but the products that are sold to control pH are themselves toxic. Strong acids or alkaloid substances have a negative effect on skin, eye, gill and mucous membranes. So why add pollution to your tank to address a non-existent problem?

    Cheers,
     
  10. roadmaster

    roadmaster Member

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    1,435
    Location:
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    I agree 100 percent. I am understanding that the small pH shifts that may occur between night and morning with the use of CO2 would be similar to that which takes place in nature and would be negligible with regards to osmoregulatory functions of fish so long as the shifts were not too drastic. Is it very difficult to dial in the proper amount of CO2 delivered to prevent fluctuations that might be considered stressful?
    Again .,I have some rather sensitive fish and am wondering ,short of storing water and adjusting it beforehand, How would you suggest water changes be done to prevent creating stress on said fish with water that may be more alkaline than that in the tank when using CO2 which I will assume will create more acidic conditions?
    I am thus far, able to keep the Discus and Rams in tapwater with pH value of 7.4 which over time ,through natural process renders my tanks pH at 7.0 to 7.2 My water is moderately hard but fish have adapted well. I am thinking smaller more frequent water changes will prevent a large shift. What type of water changes will be needed for plants to best perform with the possible addition of pressurized CO2?
    Many Thanks in advance.
     
  11. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    8,953
    Location:
    Chicago, USA
    Hi,
    Osmoregulatory issues have nothing to do with pH. Osmoregulation is controlled strictly by the level of dissolved salts. Therefore the salinity (NaCl) and Carbonate/Bicarbonate content (KH) are the salient parameters to be concerned with. You need to be aware that pH swings due to CO2 inject are actually quite enormous. In high light injected tanks there can be as much as a 10 fold or more shift in acidity, i.e. a pH shift of 1.0 unit or more within a 12 hour period. No negative impact has ever been reported. Of course, CO2 is toxic, so incompetent injection technique often leads to sudden death. That's a different issue though. Neither fish nor plant is affected by even the most brutal pH swings. That includes Discus and Rams, which many of us have kept in CO2 enriched planted tanks without any difficulty.

    When changing water, simply avoid large temperature changes. That's it. Worrying about pH shifts is much ado about nothing.

    Here is a breeding Ram in a CO2 enriched planted tank in which massive water changes were carried out regularly. These fish just carry on. They're not worried, they care much more about clean water than pH shifts.
    [​IMG]

    Cheers,
     
  12. roadmaster

    roadmaster Member

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    1,435
    Location:
    United States
    I understand what you are saying with regards to pH and have come to believe that conductivity, or total dissolved solids which may incude nutrients,minerals,salts,or organic matter are largely responsible for stress and or osmoregulatory problems when sudden changes occur. Is why we acclimate fish. Am researching problems associated with the transferring or acclimating of tropical fish to and from waters that may be high in conductivity or lower than what the fish came from. Although there are tests for such things as conductivity and or TDS, It would appear that most hobbyists,or perhaps I should say many,, rely on pH tests to indicate to some degree,the possible alkaline or acidic conditions that normally (not always) are associated to a particular reading from said pH test result.obviously one can have a pH value of say,7.8 and still have little buffering capacity but most of the time the pH value can be connected to in the case of 7.8 pH ,,a perhaps hard alkaline source.
    My research thus far is incomplete as I am still learning or absorbing. Presently also studying blood acidosis ,and alkalosis and the effects over the longterm on tropical fish and the causes which seem to point to sudden changes in water chemisrty from acidic conditions to more alkaline conditions.
    I appreciate your taking time to reply to my querys and I shall I think ,,try the high tech Co2 injected tank in the spring when plant selection is of much better quality. I fear I will need to do some further studying before I attempt to place fish in an enviornment where the daily shifts you speak of and their effect are still largely uncertain to me.
     
  13. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,953
    Location:
    Chicago, USA
    Yes, it just so happens that the carbonate salts responsible for TDS and hardness also fundamentally affect the pH since they act as buffers which sequesters H+ ions. So low pH water is typically correlated to low conductivity and high pH waters are correlated to high conductivity. But this correlation falls on it's face when we are independently adding more acids or bases to the water. One can add for example "PH Down", which can be either Phosphoric or Sulphuric acid, to the water which will increase TDS and yet the pH will fall. There are also other acids being produced by natural processes so small amounts of nitric and organic acids will always appear. In the case of CO2 injection, it's unclear what the effect on conductivity reading is.
    Again, blood acidosis has nothing to do with the pH in the water but has to do with the CO2's effect of trapping the CO2 in fishes bloodstream where the carbonic acid conversion does the damage internally. It's easy to kill fish with CO2 but it's not because the water's pH has dropped, it's because the fish cannot expel CO2 from the blood stream due to high CO2 in the water column.

    South and Central American fish are found in highly acidic waters which are driven by complex tannic acids leached from the leaf litter into the water column. These fish do not suffer acidosis, but rather, use the downward pH swings to trigger breeding. Before the widespread use of CO2 fish breeders often used peat to acidify RO/DI water in order to stimulate spawning.

    Cheers,
     

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