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The more I know, the less I know.

Discussion in 'Talk to Tom Barr' started by Tug, Jul 14, 2010.

  1. Tug

    Tug Lifetime Charter Member
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    Tom and everyone here that help sift through a lot of misinformation in this hobby, I want to thank you. What I think I know, KH stability is more important then pH stability (probably wrongish) while GH effects the osmoregulatory system.

    Should GH levels stay stable or is it more about just having enough?
    For example, the fish that we bring home - is the GH effecting how fish acclimate to their new surroundings?
    I would think matching temperature and KH are more important. :confused:

    Direct me to a more practical application or validate how these relationships (KH, pH and GH) effect caring for a planted tank full of fish. I just need some basic guidelines and direction. Maybe one or two fictional relationships that are still passed around.

    One more thing, I see on forums something about solubility of CO2 at low KH. My tack has been 30ppm is 30ppm and those who worry about CO2 solubility in water with low KH/pH read too much into the CO2/pH charts. Is there something to this misinterpretation? Does pH lower the amount of CO2 that is soluble in water, the way temperature does?
     
    #1 Tug, Jul 14, 2010
    Last edited by a moderator: Jul 14, 2010
  2. Tug

    Tug Lifetime Charter Member
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    Maybe a better way to ask this question is i am still trying to understand the relationships these units of measurement have when taking care of fish/plants.

    So, if just the basic facts or relationships could be given for each of the following;
    CO2 solubility
    pH
    KH
    GH
    Please, keep it simple if possible.
     
  3. ismenio

    ismenio Guest

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    Hi Tug, i´m not an expert but the only relationships i now is betewen CO2, pH and KH, the problem i think is read correctly the pH or KH to now the CO2, thats why is better make a 4 ºdK solution for the permanent test of CO2 rather than use the water of tank.

    But wait for the gurus please, i might be wrong.

    Regards
     
  4. Tug

    Tug Lifetime Charter Member
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    Exploding Fish

    Hi ismaeno,
    I wish it were that easy. Maybe for our purpose it is, but there are those that argue less CO2 is available to the plants in water with low KH/pH. They must be wrong, but where are they going wrong? Temperature, KH and pH have some effect on CO2, but what is it?

    Another warning I hear is that low pH is bad for some fish. I know bacteria have a hard time with a pH below 5 and waste becomes an issue for non-planted tanks. Does that mean pH isn't an issue for planted tanks? Do some fish prefer higher pH or is it just harder water they prefer?

    Is stable GH a goal or is just having enough the answer? Does a change in the GH level have any consequences? Same question for KH, why are stable levels important? Will my fish explode if I get it wrong?

    Maybe, it just depends on the circumstance, but what guides our choice and what happens when we ignore some guidelines?

    Thank you for responding. I was beginning to feel as if I was all alone. :(

    [video=youtube;5bBmIhOxxmk]http://www.youtube.com/watch?v=5bBmIhOxxmk&feature=player_embedded[/video]
     
    #4 Tug, Jul 14, 2010
    Last edited by a moderator: Jul 14, 2010
  5. ismenio

    ismenio Guest

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    Well, i understand your point, and think on this.
    Is normal to think that if we add CO2 to a tank the pH drops, and is true, but i think there is one situation that is not necessarily true, if the kH is very low 1º dH and you don´t add CO2 to the planted tank the ph will drop bellow 5, and if in the same tank you add CO2 the ph couldn't´t go so low since the plants have one better source for CO2, this happend with me and i think this is the reason why, but let´s wait for the ones who nows, i can be wrong.
    Relativity to the gh i think the main goal is supply the plants but i don´t no if affects the fish.

    Regards
     
  6. ismenio

    ismenio Guest

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    And sorry, only now i see this tread is to Tom Barr.

    Regards
     
  7. Gbark

    Gbark Guru Class Expert

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    I am also unsure of this relationship, between kh pH and CO2. I know kh and pH can be used to work out Co2, but if you take a bowl of water and add lots of kh/gh booster and some acid to drop the pH you would then have lots of co2 in the water? I don't think that this is possible unless you add some. Hence why we inject co2.

    Another sernario that i came across in my LFS, I noticed that some of the fish were gasping, and when i asked the question i got " we have added too much Kh booster" does this mean that with a higher kH it makes it easier to dissolve co2 in the water?

    not much help to you tug sorry :)
     
  8. dutchy

    dutchy Plant Guru Team
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    Carbonate hardness (KH) is the measure of bicarbonate (HCO3-) and carbonate (CO3--) ions in the water. In freshwater aquariums of neutral pH, bicarbonate ions predominate and in saltwater aquariums, carbonate ions begin to play a role. Alkalinity is the measure of the total acid binding capacity (all the anions which can bind with free H+) but is comprised mostly of carbonate hardness in freshwatersystems. Thus, in practical freshwater usage, the terms carbonate hardness, acid binding, acid buffering capacity and alkalinity are used interchangeably. In an aquarium, KH acts as a chemical bufferingagent, helping to stabilize pH. KH is generally referred to in degrees hardness and is expressed in CaCO3 equivalents just like GH.

    GH is primarily the measure of calcium (Ca++) and magnesium (Mg++) ions in the water. Other ions can contribute to GH but their effects are usually insignificant and the other ions are difficult to measure. GH will not directly affect pH although "hard" water is generally alkaline due to some interaction of GH and KH.

    GH is the more important of the two in biological processes. When a fish or plant is said to prefer "hard" or "soft" water, this is referring to GH. Incorrect GH will affect the transfer of nutrients and waste products through cell membranes and can affect egg fertility, proper functioning of internal organs such as kidneys and growth. Within reason, most fish and plants can successfully adapt to local GH conditions, although breeding may be impaired.

    pH is determined by the concentration of free hydrogen ions (H+) in the water.If we add nitric acid to reduce pH, the hydrogen ions freed in the reaction then increase the concentration of hydrogen ions. Since nitric acid is the end product of the nitrogen cycle, this explains why aquarium pH tends to decrease and nitrates tend to increase over time.

    When the aquarium has some carbonate buffering in it, the bicarbonate ions will combine with the excess hydrogen ions to form carbonic acid (H2CO3) which then slowly breaks down into CO2 and water. Since the excess hydrogen ions are used in the reaction, the pH does not change very much. Over time, as the carbonate ions are used up, the buffering capacity will drop and larger pH changes will be noted. From this it is clear why aquariums with low KH seem unstable - as acid is produced by biological action, the KH is used up; when it is gone, the pH is free to drop rapidly as H+ ions are generated.

    The rise in pH that occurs when KH is added will be balanced to a degree by the dissolved CO2 in the water. Fortunately, CO2 is also a result of the nitrification process and fish and plant respiration so it is readily available. The CO2 will form small amounts of carbonic acid and bicarbonate which will tend to reduce the pH. This mechanism gives us a way to regulate pH in the aquarium.

    If the pH of an aquarium is determined PRIMARILY by the carbonate buffering system, then the relation of pH and KH and dissolved CO2 is fixed. You can change either KH or CO2 to set the pH, this depends if you're using a CO2 system or not. The dissolved CO2 level has no effect on KH.

    I hope this makes it more clear.

    regards,
    dutchy
     
    #8 dutchy, Jul 15, 2010
    Last edited by a moderator: Jul 15, 2010
  9. ismenio

    ismenio Guest

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    Hi Dutchy, thanks for yours explanation.

    So, in planted tanks with injection of co2 we can not use the relation of co2/kh/ph to find the co2 we have on tank.

    But relatively to gh, you say that affect the fish but is better have a high gh for the fish or low ?

    Regards
     
  10. dutchy

    dutchy Plant Guru Team
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    Theoretically, we can. The only thing that messes it up is that everything that influences pH, like nitric acids, will give you a pH reading that you can't use to determine CO2 level. Here's where people that use the pH/KH chart to determine CO2 go wrong.
    I think there's no specific rule for that. Every fish has it's own natural GH range, depending on where it originally came from. Captive bred fish are less sensitive here and more tolerant to live under different GH values. Personally I do take this into account when I buy wild captured fish.

    regards,
    dutchy
     
    #10 dutchy, Jul 15, 2010
    Last edited by a moderator: Jul 15, 2010
  11. ismenio

    ismenio Guest

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    By the way, now i´m confused with a thing.

    Lets suppose the ph and kh that i have on my tank says by the co2/kh/ph table that my level of co2 is good, i must use the injection of co2 ?

    I hope that you understand my question.

    Regards
     
  12. dutchy

    dutchy Plant Guru Team
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    I'm not sure I understand what you mean, but I will try.... Forgive me if i missed the point.

    The CO2/KH/PH table will just be anyones best guess about how much CO2 you have. I can give you a nice example. The pH in my tank is 6.2 and the KH 5. Now look at the chart and see how much CO2 that is. Probably that value is not even on the chart!! And if it is, you can see that all my fish should be dead, theoretically. But they are not. Even my discus, known to take a max of only 40 to 45 ppm, are doing very well.....

    So something must be wrong here. It could very well be that my pH is on a lower level that's not caused by CO2. So I go for the level which my discus can take, which will give me around 40 ppm of CO2. Fish are the best test kit ;)

    regards,
    dutchy
     
  13. shoggoth43

    shoggoth43 Lifetime Charter Member
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    You never HAVE to use CO2. It's just that the chart that uses the CO2/kh/ph will most likely not be accurate. For example, if you use the chart, and someone added nitric acid or maybe even vinegar into the tank, then your pH reading according to the chart will tell you that you have much more CO2 than you actually have. You will almost always have other processes going on other then just the KH/pH variables in the chart would indicate. This is where people say they KNOW they have enough CO2 in there because of the chart. When they then throw in a drop checker they find they're almost never even close to what they thought they had in there. Essentially, ignore the chart. It's only good in very specific circumstances and most of the time is not applicable to most tanks. They only way to get enough CO2 usually is to add it somehow. Whether you can do this via surface movement ( in some cases ), lack of surface movement, or CO2 injection
    will depend on your tank and how you've set it up. It can be done both ways and the place to start is with how much light you have over the tank. More light = more CO2 demand = more nutrient demand.

    I'm not sure if I really answered your question though.

    -
    S
     
  14. hbosman

    hbosman Guru Class Expert

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    I've read that phosphates will alter ph readings. Do phosphates act as a buffer and increase ph or is it the opposite?
     
  15. Tom Barr

    Tom Barr Founder
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    Virtually every case of effects on CO2 give false positives, in other words, they make you think you have more CO2, than you really do.
    I have never seen a case where a test or interference added more CO2 than the test suggested.

    It's always less than you think or equal never more.

    Poor accuracy test might lead to a little on the underestimating side, but not much.
    Anything that messes with pH or reduces it will make you think you have more CO2 than is really there(well, other than CO2 itself obviously).


    Regards,
    Tom Barr
     
  16. hbosman

    hbosman Guru Class Expert

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    So, adding more KH2PO4 would probably reduce the ph?
     
  17. Tug

    Tug Lifetime Charter Member
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    Keep those questions coming

    I'm glad to see this thread moving along, but I would hate to see any of the questions get passed over. Maybe I should have called the thread things people say that make no sense. So, please look through the thread for unanswered questions, common misconceptions and clear them up for me. Who can answer this one,
    What was that LFS salesman talking about?
     
  18. Tug

    Tug Lifetime Charter Member
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    Another one I come across, "my pH is high, I must have hard water." What's wrong with that statement? And, as far as fish are concerned is the pH less a concern as long as the GH is appropriate?

    If you find any of these questions don't make sense, make a sensible question out of it if you can. ;)
     
  19. ismenio

    ismenio Guest

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    Thanks to all of you.

    I have finally understand, i must use a drop checker with a 4º dk solution.
    Must forget the co2/ph/kh chart since there is on the water other compounds that will alter the results.

    Thanks
     
  20. dutchy

    dutchy Plant Guru Team
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    Hi Tug,

    As to the KH booster, I think the fish will experience the same as too much CO2. I'm not sure if it gets easier to dissolve CO2 with a high KH, but I do know that it takes more CO2 to reach a certain ppm level if KH is high. Maybe the KH booster, which is a C-source, takes O2 to bind to and causes an O2 shortage for fish if overdosed.

    pH and hard water is comparing apples and oranges as hard water refers to the Ca level. This comes from the "DH" which is, free translation: German Hardness. I can have a pH of 6.2 with a GH of 8, but after some hours of no CO2 the pH will be 7, but the GH still 8. Still even over here people refer high pH with "hard" en low pH with "soft".

    I'm not sure if pH is of less concern than GH for fish. I think captive bred fish are not very picky and tolerate a big range in pH and GH values. Maybe it has an influence on breeding.

    Pls take into account that I'm not a biologist or chemist, I'm just writing what I (think) I know, and could also be based on misconceptions. ;)

    regards,
    dutchy
     

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