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Pearling - how important as a guide?

Discussion in 'CO2 Enrichment' started by Gerryd, Jun 4, 2008.

  1. Gerryd

    Gerryd Plant Guru Team
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    Hi all,

    Question about pearling.

    My tank is doing really well right now. No algae (knock head/wood), good growth, leaves nice well formed, etc.

    Two DC moved around the tank over the last couple of days indicate I have good c02 throughout the tank, including the bottom. Green color all over.

    So, my riccia does not pearl as my MH are now 44" above the substrate and they used to be 34". It used to pearl at the lower height.

    Question is this:

    If all other visual indicators are good, plants/fauna healthy, good growth, clear water, DC color, good c02, nutirents ok, etc, but NOT ALL plants pearl, is this an indication that they do not have sufficient light to pearl?

    Or that I am still lacking in some nutrient or the other?

    I would LOVE to see my Riccia sparkle again, but since the tank is doing very well for me, I hesitate to lower the light just to make this happen.

    Thoughts, opinions, comments are all welcome.

    Thanks in advance.
     
  2. Carissa

    Carissa Guru Class Expert

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    If it happened when you raised the light, then it definitely sounds like more of a lighting thing than anything else. If there was a deficiency of some kind, it probably wouldn't pearl at all, no matter the lighting. In my tanks, with lower light, it is often only the top 1/3 of the leaves on the plants that pearl. Not pearling just means it's not growing as fast, it doesn't mean it's not growing at all or not healthy. Adding enough lighting to get all plants to pearl all the time could end up throwing other things off balance, so there's a trade-off somewhere. Personally I wouldn't worry about it, unless you see other signs of a problem.
     
  3. Tom Barr

    Tom Barr Founder
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    As Growth rates are amplified, so will the presence of pearling.

    I use pearling as an indicator of "rapid growth rates", not really "good health".
    However, with CO2 and high light, if I do not see it fairly soon after the lights come on, I know something is amiss.

    I can do a large water change, adjust/add the nutrients back to k nown levels.
    If that does not work, then I know it's CO2.
    Pretty simple to deduce what it is then.

    Some test their CO2 and think that's it.
    They reset their their nutrients and think the nutrients must be causing the issue and test those.

    This can lead to many myths.
    Folks go back and question the nutrient ppm's.
    Now obviously if you reduce the nutrients far enough down, you can reduce CO2 demand as well.

    But what about CO2?

    1. How well and accurately is it really measured and over what time frame is it important?
    2. Some suggest adding more will cause their fish to gasp or die etc, this can be resolved by adding more current and some more surface movement, good flow and mixing in the tank and a steady supply of CO2.
    3. Now go back and see if the old higher levels of nutrients still cause the same issues for you.........

    Curiously, anytime I do this test, I have the same results and have for decades.
    A water change and the pearling thereafter is a good indicator that you can improve something. Nutrients are fairly easy to rule out, CO2 is not too bad either, but folks seem to enjoy playing with NO3 etc more.....

    Just realize what you see when you limit one nutrient on purpose, and assume that the CO2 was non limiting prior, the chance of making an error is rather high.

    This single issue has caused many folks to butt heads with me more than once over the years. However, I can prove I'm right and have effectively for over a decade on this topic.

    You have issues with plants and algae mostly from limitations to growth, not excesses which have pretty high ranges before they are detrimental.
    So if you have CO2 limitation, then you limit some other nutrient, the limitation switches and while there is certainly correlation, the mistake is made when they often assume it to be direct cause.

    Careful in assuming what the pearling is caused by or not.
    CO2 is the largest driving factor in producing/controlling aquatic submersed plant growth rates. Every Aquatic Botanist will tell you this and rightly so.

    But there's always some aquatic plant person that will bemoan nutrients and fall into the trap.

    Regards,
    Tom Barr
     
  4. Gerryd

    Gerryd Plant Guru Team
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    Carissa,

    Yes understood, all the top half pearls well for me.

    I get caught up sometimes when I see those pics where there is pearling all over the place. You know what I mean...Then I think mine has to be the same, or is not good somehow....

    It was definitely the height adjustment, all else being equal.

    Tom,

    This comment hit home for me and I think is the key for me:

    Like Carissa said, doesn;t mean it is not healthy growth.

    Yes, within 10-20 minutes, I can see pearling. Very good within 60-90 mins.

    I am being more careful not to assume, or as you said when I first came on the site:

    'Don't believe everything you think either'. Which Carissa liked as I remember.

    Thanks again for all of the great help and info.
     
  5. Tom Barr

    Tom Barr Founder
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    Also, most pics are taken after a few water changes, cleaning etc, so they are idealized situations.

    Do a massive water change in the morning(30min before lights come on) and add higher than normal ferts, crank the lights and take the pic later in the day.

    ADA uses a lot of the studio lights as well. These drive the plants at higher rates of growth while taking the pics. Hard to get enough light for photos.


    Regards,
    Tom Barr
     
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