CO2 MEASUREMENT USING A DROP CHECKER

Discussion in 'Tutorials' started by ceg4048, 4 Nov 2007.

  1. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    As long as you restrict the dropchecker's sample water to 4 dkH as suggested in the article the content of the tank water is completely irrelevant. Now, you should not be using any buffers at all as these are pointless. Neither fauna nor fauna care about the pH of the tank water so using buffers is a complete waste of time and energy. Having said that however, the whole purpose of the dropchecker is to isolate the measurement sample from the tank water. The buffers added to the tank water cannot easily find their way into the dropchecker water sample. Only CO2 and other gasses evaporate from the tank water into the air cavity inside the checker and then down from that air cavity into the sample water. Therefore there is no need to worry about the composition of the tank water. As long as you do not add buffers to the dropchecker itself you have no problem.

    Cheers,
     
    Zak Rafik likes this.
  2. lljdma06

    lljdma06 Member

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    I know this a little while ago, but very smart thinking. :thumbup: Good food for thought for those growing lawncovers. When I finally setup the Dutch, I'll heavily consider placing the drop checker near the HC to closely monitor whether the levels are adaquate down there.

    The only problem I forsee is an entire tank full of drop checkers to measure CO2 levels in various locations. :crazy: Would be an interesting experiment, though.

    llj
     
  3. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    Well, that too would be completely over the top. The drop checker is a guide, which illuminates the path. It's an excellent reference, but it cannot tell you much more that what you can already determine by simple observation of plant health. If your carpet plants are turning brow or are not growing well then you know immediately that the issue is insufficient CO2 and that it's allocation to the carpet area must be adjusted, regardless of the dropchecker readings.

    Cheers,
     
  4. lljdma06

    lljdma06 Member

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    You know I'm joking right? Who would have a tank full of drop checkers? :lol:
     
  5. Egmel

    Egmel Member

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    I too live in a hard water area (pH is around 8, 16.5DH, I can't remember the GH off hand and Thames Water don't give a rating for that on their site) but I've kept Rummy Nose tetras for the last couple of years without any problems.

    I've never used buffers, the general gist is that stable pH is more important than any specific pH. Since a lot of people use CO2 on a day time only basis I'd guess that what the fish actually need is stable hardness rather than stable pH since they don't seem affected by the pH swings caused by adding CO2. This is a totally untested hypothesis though, just something that seems likely from what I and others have experienced.
     
  6. Ed Seeley

    Ed Seeley Member

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    I think you're nearly right Egmel, but I don't think it's just the hardness but the TDS that is a more important factor. I don't like to have the GH, KH and other dissolved solids swinging around in a tank, but I don't mind pH swinging around due to CO2. Bear in mind that if your pH swings due to other factors then pH is an indicator of something else changing and that may be the cause of problems; pH changing in itself is not the problem.
     
  7. Egmel

    Egmel Member

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    TDS = Total Dissolved Solids?
     
  8. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    Correct! :thumbup:

    Actually, TDS will change constantly depending on waste production, nutrient addition and so forth. GH will change based on calcium and magnesium uptake/production. These shouldn't be wild swings though, otherwise, as Ed notes, this indicates some dynamic occurring. KH movement has the highest impact because it plays a direct role in osmoregulation. So in troubleshooting breeding and health issues it really depends on why TDS/GH/kH/pH are changing.

    Cheers,
     
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  9. andyh

    andyh Member

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    Where in the UK are you guys getting your 4 dkH water from? I had a quick look and couldn't find any:?:
     
  10. aaronnorth

    aaronnorth Member

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    aqua essentials or make your own

    Add 6g of pure Sodium Bicarbonate to 5l of DeIonised water (DI) to give you a solution at 40dKH.

    Mix 10ml of this solution with 90ml of 'fresh' DI to give you 1l of 4dKH reference solution.

    This obviously makes a lot, so you can sell some on (providing it is accurate),

    you can scale it down but it gets less accurate the more you do so.
     
  11. jarthel

    jarthel Member

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    Hello. can someone please explain why the checker needs to be in front of the tank?

    thank you
     
  12. Dan Crawford

    Dan Crawford Founder Staff Member

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    So that you can see it properly and gain the best representation of the colour.
     
  13. jarthel

    jarthel Member

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    so I suppose if it's attached on the side, it looks different? thanks again
     
  14. aaronnorth

    aaronnorth Member

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    Hi, the reason Ceg has attached to the front is probably to take the pictures, if you look at some aqauriums on here they are attached to the side as to not disrupt the view.
     
  15. sWozzAres

    sWozzAres Member

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    My tap KH varies from 6 to 13 so everytime I complete a WC I have to reset the DC. This involves alot of effort in tweaking and monitoring and by the time you've got it sorted, it's time for another WC. Imo this makes DC impractical. At one end of the scale your in real danger of killing your fish and the other, inducing algae.

    Since EI is a proponent of the "no test kit" methodology, I often wonder how many other people have the same problem and aren't even aware of it.
     
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  16. Garuf

    Garuf Member

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    you have to reset the drop checker? A drop checker is a known value, never a influenced measure, ie. tank water? How'd you mean? Do you mean that because you've changed the water the co2 capacity of the waters changed or what? I find it difficult to folow if you're using a dc correctly as little more than an indicator.
     
  17. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    Errr..as stated in the article the dropchecker should be filled with distilled/RO water adjusted to 4 dKH. If you use tank water or tap water then you will have trouble.

    Yeah, you're way off the beaten track if you're having this much difficulty. I think you need to review the article, maybe a couple of times.

    The people who use tap water or tank water are the ones who have this problem. Setting up the dropchecker is a finicky affair but there is no rocket science involved here.

    Cheers,
     
  18. arty

    arty Member

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    Thank You Clive for this great post, realy good post.
    I will add only some words from my expirience, possibly some one have same effects.

    1)Once fitted dropchecker under water canot be removed out and again submersed under water, then readings sometimes wrong, why - i don't know :).
    2) Dropchecker needs be perfectly clean before top with 4dkh solution and br. blue.

    Best Regards,
     
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  19. sWozzAres

    sWozzAres Member

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    Clive, you misunderstand, I should have been clearer, when I say reset DC I mean reset bpm in terms of my changed KH by monitoring the DC. Of course I use 4dKH in the DC!! Since the tank KH can change by a few degrees (depending on current tap KH and % WC) then keeping the same bpm results in a different minimum pH/maximum CO2. As an example, the last WC resulted in a tank KH change of 9 to 12, which is considerable. Trying to then get DC colour the same as before is therefore time consuming, finicky as you say. When you combine the fact that DC is delayed, the colour is subjective in terms of eyes and tank light and you can only really tell if bpm is correct once CO2 injection matches escape/absorbtion rate which changes depending on plant growth and surface movement and might only happen once each day, then you can easily have more than a few days where CO2 is considerably different to what you had before. Since lifestyle dictates how much time you can sit around and monitor the thing, a considerable KH drop after WC can kill your fish, yes I am paranoid but I make no excuses for that :)

    good article btw

    Thanks...
     
  20. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    Well, whatever bubble rate you had before the water change should be the same rate more or less what you set it to after the water change. The KH of the tank water does not matter. For example, a bubble rate of 3 bps puts exactly the same amount of CO2 in the water whether the tank water was 6KH or 9KH. This will also not affect the colour of the DC. A 6 KH tank water with 30ppm CO2 will cause the dropchecker to be exactly the same colour as a 9KH tank water. The CO2 simply off-gasses into the air space of the DC and then diffuses into the 4 KH water.

    Naturally, when you do a water change, and if you clean/reset the DC, then yes the colours will be all wrong, but that doesn't matter because the needle valve setting will be the same. Water changes actually introduce CO2 into the tank. The tap usually has plenty, and when the leaves are exposed to air they gather CO2, so it doesn't matter that the DC will take a few hours to come up to speed. Energize the solenoid and you'll be back on track.

    I'm probably stating the obvious but when you do the water change you should simply de-power the solenoid, not close the needle valve. That way it preserves the needle valve setting.

    Cylinder valves and needle valves are not perfect. As the cylinder empties the needle valve output drifts forcing you to make slight adjustments to the needle valve. This is definitely irritating and that may be the true value of brand name regulator components as opposed to the knock off ebay brands. Since I'm too cheap to pay for name brand regulators I can only go by what others have reported, but I suspect this is true. Some people report a higher incidence of BBA for example, which may in the long run be traced to an under-performing needle valve.

    I agree with what you say, but one of the keys to better technique is understanding what the tank is telling you and to know how to identify the imminent warning signs. Imagine, for example those who are not aware that BBA, filamentous and often GSA are CO2 related. Or imagine those than are not aware that structural failures and deformation are CO2 related? Unless there is a sudden and obvious CO2 malfunction, the tank will tell you what's happening before things get out of hand. When you understand the signs, take immediate action but don't panic. Reducing lighting combined with CO2 injection rate increase will typically save the day.

    You just have to decide that CO2 monitoring and adjustment is integral to your daily procedure and to treat it that way. If I spend 30 minutes every morning on the tank, 10 minutes is dedicated to removing leaves/debris, 5 minutes to fluffing/preening, 2 minutes to dosing and then the rest is checking/adjusting CO2. In my tanks, the first warning sign is typically a strand or two of hair on the highest leaves waving at me like a pirates skull & crossbones flag. I'll immediately make a slight upwards adjustment of the needle valve. After a while, you do get a feel for how much adjustment of this valve you need. In the end, it really is the plants themselves that talk to me, not the DC, which is entirely consistent with my "do-not-depend-on-test-kit" mentality.

    CO2 is so critical in a high energy tank that there is a wide gamut of failures attributable to it's misapplication. There is a category of symptoms for slight, subtle failures, another category for medium or chronic failures, and another category for acute (bonehead) failures. This is what prompted Barr to suggest that if you have a plant failure in your tank, then there is a 95% probability that it's one of those categories of CO2 misapplication.

    Hope this helps. :crazy:

    Cheers,
     
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