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Is pearling a continuous process?

Discussion in 'CO2 Enrichment' started by qsaark, Feb 23, 2007.

  1. qsaark

    qsaark Junior Poster

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    I understand that pearling happens because of photosynthesis. In the presence of light, plants consume CO2 and produce O2 that is released. Now my question is, under optimum conditions (light, nutrients, CO2), is pearling a continuous process in a healthy aquarium? I observed strong pearling when I increased the light from 2.4 to 4.6W/G. However the pearling lasted for two days after which it stopped. Now I only see small bubbles underneath the leaves of my plants. No change in light, CO2 etc.
     
  2. Frolicsome_Flora

    Frolicsome_Flora Guru Class Expert

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    4.6wpg Waaaaaaay too much light. Youll find that the plants were just taking advantage of the suddenly available high light. If youve not upped the CO2 AND nutrients to compensate for the massive light, then the plants wont be able to get enough, leading to deficient growth in whatever runs out first, probably CO2..

    Turn the light down, let the plants get used to 2.4wpg with good solid CO2 and EI (this takes some time), theyll be pearling nicely after a few hours of lighting. A good solid stable slower growth, is far better than trying to run the tank at 400 miles per hour, running out of CO2, having massive algae problems, awful looking plants.. but lots of bubbles.

    Also bear in mind, some plants dont pearl as much as others do anyway, Riccia is a very good indicator as to how you have things setup. If you see lots of nice little bubbles by 1/2 way through your photoperiod, leave it be.

    A wise man once told me.. 'The only things that happen in an aquarium fast, are BAD'
     
  3. qsaark

    qsaark Junior Poster

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    Although I am using 4.6 W/G, the lights are hanging 8" above the tank. I switched to high light because my Rotala rotundifolia, Ludwigia repens, and pearlgrass were not doing well. After increasing the light, I have noticed a considerable difference in their growth and color. I also increased the CO2 from 21ppm to 30 ppm.
     
  4. Frolicsome_Flora

    Frolicsome_Flora Guru Class Expert

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    We have no way of determining how much CO2 we have to that accuracy. If your using the KH/PH relationship, then you have between about 10-40 ppm. the only way to be sure is to use a drop checker with a KH reference solution.

    Thats still a heck alot of light.. its more likely your plants were struggling for other reasons other than light. Nearly all plants will grow at 1/2 that.. its more than often CO2 thats the issue.. test kit methods of measuring are totally pointless due to the inaccuracy and other factors in the tank that can effect PH.

    Dose with EI, then all you have to worry about is CO2.. use EI and a drop checker, and youll be amazed.
     
  5. qsaark

    qsaark Junior Poster

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    what is EI?
     
  6. Frolicsome_Flora

    Frolicsome_Flora Guru Class Expert

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    its a method of nutrient dosing called the Estimative Index. It allows us to provide nutrients in a slight excess, without the need for any test kits, or general messing about. This means that it gives us far far less to worry about.

    Have a look at the Estimative Index discussion for details :) itll change your aquariums life!
     
  7. Tom Barr

    Tom Barr Founder
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    So was it due to adding more CO2, or was it due to the increase in lighting?

    Why do you think that the pearling and good growth only lasted 2 days?
    You ran out of something. It was not light and does not sound like it was CO2 either.

    NO3
    PO4
    K+
    Traces
    Ca/Mg

    See the EI article, it makes adding these very easy and rules out deficiencies as well as excesses in a couple of very simple steps anyone can do and does not require testing or chemistry knowledge.

    Tell me the tank size, I'll tell you what to add and how frequently.
    Ideally, after a large water change, there is a lot of pearling and you should try and see if you can attain that same growth and pearling all week long.

    If it backs off a tad, that's okay, but the tank should pearl good most of week and after 1-4 hours if you use higher light/CO2 etc.

    Riccia is a good indicator plant for pearling also.

    Regards,
    Tom Barr
     
  8. qsaark

    qsaark Junior Poster

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    Tom, thanks for the reply. Well, I have a 10 gallon tank. I use Hagen plant grow fertilizer (5ml/10 gallon) once a week.

    Slightly off-topic, however, as Frolicsome_Flora suggested, I should use a drop checker for estimating the CO2 levels. I was thinking of making a DIY drop checker. I hold a PhD in molecular biology and therefore work in a lab where we use ultra-precise intrument and extremely pure chemicals (molecular grade). Now as I understood from some the topics, I have to have a vessel containing NaHCO3 solution in deionized water equivalent of 4dKH. That is 50mg/L NaHCO3. Purity and correct measurement is not my problem. So if 4dKH is 50mg/L, I'll jolly well make this solution. Then I have to add few drops of pH indicator. I could use Bromo thymol blue or Phenol red. And then I have to enclose this solution in a vessel that is made such that the colored solution is in ocntact with aquarium water via a gas phase. Correct me if my understanding is OK.

    Thanks.
     
  9. VaughnH

    VaughnH Lifetime Charter Member
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    You can't use Phenol red as an indicator solution and still use 4 dKH water. That KH was chosen to make the solution be at it mid-point on the indicator color chart at 30 ppm of CO2. Phenol red's mid-point is about 7.3 pH, which would require a 20 dKH solution in the bulb to reach the mid-point at 30 ppm of CO2.

    And, it is important that the drop checker be entirely submerged in the tank water, to avoid any distillation between the water in the drop checker and the water in the tank.

    I think you have the ppm of NaHCO3 wrong also, but I could be mistaken. I think 1 dKH = about 18 ppm of CO3. I admit that I am no chemist, and I get the relationship between ppm of sodium bicarbonate and dKH confused.
     
  10. Tom Barr

    Tom Barr Founder
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    Well, if you are molecular person, then it's easy. I just went through the core molecular plant bio grad group here at UC Davis, I got a lot out of it.

    You got the idea.
    Just take a test tube and bend it in 1/2 making a nice even bend(pack the test tube with sand, this will prevent kinking when you bend it, about 1.5" for the bulb end and 1" for the open end.
    10-12mm tubes will work fine.
    Add a glob of glass for the suction cup.
    Cool and then use.

    Use sodium carbonate instead if you have that type of access.
    Make a few also, different sizes if you have various test tube sizes available.

    With good equipment, you ought to be able to make a 71.440ppm solution of alk pretty easily(carbonate hardness) with a scale and DI water and Na2CO3.
    You can make a high concentration, so 40KH, or 714.400ppm.

    Make a liter, then dilute by one order of magnitude to make a liter of 4KH.
    Add to the bulb(6mls), and then use the Bromo blue, it's precise in the range we want, generally used for 6.0-7.4 pH ranges which is right in the middle of a KH of 4 or 5. You do not have to make a 4KH, you may use 5 or where ever your perception of color is best.

    I use the KH solution and then a pH meter as it's accuracy is much better and responsive to pH changes. I use a Dissolved O2 membrane wrapped around the pH probe tip, in place of the KCL electrolyte, I use Na2CO3 electrolyte KH ref solution.

    Gas (but not the tank water and KH solution) travels across the DO membrane and then the pH is referenced to the 4 KH reading.
    It does not matter if the gas is N2, Ar, CO2 or O2.
    Only the CO2 will influence the pH.

    There is no phase change time issues this way. That is a hard issue to overcome, it works but the best you might hope for is a 1-2 hour response time with a drop checker. The pH meter is a few minutes.

    But drop checkers work on a practical level very well, so I'd certainly suggest you make on. They will be time savers later.
    I think 6mls of KH solution in the test tube drop checker, 3 drops of the bromo blue ought to do it.

    All this stuff is cheap and easy for you to DIY at the lab.

    Back to the original question:

    Many folks will state that pearling is due to when the saturation values of O2 are above 100%, this is not true.

    It's only when the rate of dissolution of O2 produced from the plant's growth is exceed by the production of O2 due from plant growth. Then gas phase forms and builds up into bubbles released from the plant leaves.

    Growth is generally defined as an irreversible acquisition of carbon, and photosynthesis can be measured via the amount of O2 dissolved into solution(even if it's well over 100% which is often the case with aquatic macrophytes/microalgae blooms etc).
    So as carbon is fixed, O2 is released via our old photosynthesis equation:

    6H2O + CO2 and some light/enzymes => 6O2 + C6H12O6

    So O2 correlates very well with growth(sugar production via photosynthesis) in practical terms and theoretical.

    But when plant growth is good, and O2 levels are low, you can easily have pearling without being near 100% saturation levels with the air. Pearling just means the rate of O2, or growth, is fast enough to make bubbles of O2 that we can see. If that rate is fast, it will not matter that much what the saturation level of O2 is in the tank, O2 is not that souble compared to other gases like CO2 which is very soluble in water.

    So pearling is a sign of strong growth, watch for it carefully.
    Some folks down play it, thinking bubbles come from other sources, there is some debate about that, but after doing it awhile, you can discern between growth and just funny bubbles, anyone with a decent eye can see the differences.

    If you use an O2 meter, the main device we use to measure productivity in aquatic submersed systems, then you can show this in aquariums as well, this gets around the other gas argument easily and quantifies submersed growth.

    By doing a bottle test(it has a few issues, so take with a grain of salt), you can get the dark respiration rates also. Instead of suspending a pair of test bottles(one wrapped in 2 layers of foil) in the water, we use a jar covered with foil and another open to the light and place a DO meter inside this with a grommet.

    This jar is open at one end and we push in around the plant bed and do the same with a foil covered jar close by.

    Gross O2 (light bottle) - the Respiration (dark bottle) = primary production rates.

    One thing that has not been done, is this type of test in aquariums over a wide range. Most only measure gross O2.

    The DO meter allows you to measure in real time continuously the changes in both the production and respiration of the system.

    Most test tend to use test kits rather than DO meters and only measure a before and after reading of a specified amount of time. The rate of growth can decline due to the treatment with the jar, nutrient limitations, CO2 limitation is a big one etc.

    We can get around this by doing it and measuring CO2 closely (the other nutrients are not likely to be depleted in a few hours except CO2) at the same time.

    We can also do shorter time frames and measure with more precision using a DO meter and the CO2/KH ref methods.

    That's where I'm going hopefully later.
    I know some folks tank';s are over loaded with fish and their respiration rates are very high, whereas some folk's rates are very low. No one has really done much here with respect to this in aquariums.

    I have the equipment, methods and know how to do this
    Oh, the important one, the willingness to do it!
    The biggest issue of them all.

    Regards,
    Tom Barr












    Regards,
    Tom Barr
     
  11. qsaark

    qsaark Junior Poster

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    Since I work with bugs (microbes, viruses etc.), my botany is rudimantery. However, if I have to take this hobby seriously, I have to read about plant physiology which I will in due course of time. Nonetheless, great discussion. Please tell me more about fertilizer dosing as you mentioned above. I have a 10 gallon tank stocked with Java fern, Java fern lace, Rotala rotundifolia, Ludwigia repens, Pearlgrass, and some dwarf hairgrass. Since I admire plants more than fish, I have only 3 Neon tetras and 3 ghost shrimps.
     
  12. Tom Barr

    Tom Barr Founder
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    Well, you can pick up a text book, but the issue is then how to apply all that to our specific area of interest.
    That's quite another matter.
    I had a lot of issues looking things up and then trying to locate and apply these things to our specific application. I know what to look for and where these days, back then I did not.

    There's very little done in the research in this context, aquatic horticulture of submersed plants for ornamental growth inside our homes.

    I try to synthesize the practical stuff, add enough science to allow for some more learning/stretching of the mind and leave some room for folks to look at the broader picture hopefully.

    No one writes anything about aquatic plants like that, just some of the same old mumbo anyone can pull off any plant site. Nothing new or interesting ideas about how to test for/resolve questions, new areas that might warrant more attention and play a larger role than we might have considered.

    Just getting aquarist to question the accuracy of those 5$ cheapo test kits and to calibrate them is a huge task. Most assume those are accurate and infallible.

    For the 10 gallon tank:

    I'd add
    1/8 teaspoon KNO3 3x a week
    1/32nd(about a BB's worth) of KH2PO4 3x a week
    GH booster, about 1/4 teaspoon after the water change
    3 mls 3x a week of a trace mix like Tropica Master Grow(TMG)
    Weekly 50-60% water change etc.

    That it.

    I'd buy some Amano shrimp(4-6).
    These will do better for algae etc.
    Most find them more interesting than the Ghost shrimp.

    Since you like the microbes, you will find this article on nitrifying bacteria illuminating.

    This one is particularly good and shows even old stuff that most aquarist even 1 decade later still cling too.

    Tim is good at this and has a good job in his field with Aquaria Inc.
    I also went to UCSB like Tim but did an BS in Aquatic Biology.

    http://www.marineland.com/science/peerpapers/Hovanec1.pdf

    http://www.marineland.com/science/peerpapers/AEM_Dec01.pdf

    http://www.marineland.com/science/peerpapers/McDevitt4.pdf

    And this one points out some of the major issues with the myths most aquarist still to this day assume about Nitrogen filter bacteria:

    http://www.marineland.com/science/peerpapers/hovanec2.pdf

    All about bacteria and somewhat and ecological molecular approach to bacteria.
    Should be easy reading for you, after doing plant molecular work for a year, it makes a lot more sense today:)

    But I also heard Tim speak at a club meeting on this topic and he made it very understandable for the lay aquarist. Most of them wondered off amazed and somewhat disconcerted about their long views being shattered to small little pieces. Tim did good work, saw it, went after it and was easily able to say something meaningful to the hobby that advanced the knowledge a good deal on the basic fundamental things.

    You might also consider reading the BarrReport news letters(there's 25-almost 26. about 10 pages each) which are sort of general review papers on each topic.

    Give them a read and see.
    No rush, they will take time but they are good reading and you will learn a lot from it.

    Regards,
    Tom Barr
     
  13. qsaark

    qsaark Junior Poster

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    I dont get your argument about phenol red. As I understand, KH is defined as the carbonate hardness of the water. Scientifically, however, it is the buffering capacity of carbonate/bicarbonate buffer. Now ideally, we should use a pH indicator in a solution that closely mimics the buffering capacity of the aquarium for wich a change in the pH is being tested. So if the buffering capacity (or KH) of the tank is 4, we should use the indicator in a solution having the same KH that is 4. Upon the exposure of a pH altering agent (CO2 in this case), the dye will change its color. If we use lets say 20 dKH solution, you are essentially using a solution of a different ionic strength. Since the ionic strength of the 20 KH solution is 4 times as high as that of 4 dKH, more concentration of a pH altering agent will be required to see a change in the color. I may be wrong, but I think it should work like that.
     
  14. qsaark

    qsaark Junior Poster

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    Absolutely right. That is why I have joined these forums to learn from the years of experience of people like you.

    I am thrilled to learn that you actually go through the scientific literature. Let me go through these papers, I'll discuss with you. No wonder, I expect a UC Davis graduate to be like this.
     
  15. Tom Barr

    Tom Barr Founder
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    The notion about the Phenol red vs bromo blue is really one based on the KH/pH range you want to use.

    I think it's best we just pick the bromo blue range.
    That is the most common and the best narrow range for our purposes.
    But one could use another pH indicator if they are so inclined.


    Yes, I do go through many papers to do the articles.
    I cite things, they are hardly up to the level of an independent peer reviewed paper mind you, it'd be tough to write at that level every month and have a job and go to school full time 1 year away from a PhD. :rolleyes:
    I would not suggest it to anyone.

    But they are far better and put many of the pieces together in a decent model. Later, some one else will put more of the pieces together in a more cohesive manner.

    Still, it does lay a good foundation to work from.

    There is an aquatic microbiology sub forum section here as well.
    I tend to post various papers for folks to mull through on there and elsewhere here.

    Then I try and draw from those and figure out if it helps and we can use it or not.
    About all we can do really and test ourselves here and there.

    Regards,
    Tom Barr
     
  16. qsaark

    qsaark Junior Poster

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    Just wanted to update. The plants are doing very well now. Following Tom's advice as described in few posts above, I increased the fertilizer (CO2 is ~ 30ppm). Though algal bloom is also noticed but just brown and could easily be removed by regular wipes. Water change was not of much help in this regard. Few isolated but tougher green spots of algae also appear time to time but well under control.

    By the way, I have bought Tetra Algae Control. I has Poly[(oxyethylene(dimethylimino)Ethylene(Dimethylimino)Ethylene Dichloride] as its active ingredient. They suggest to use 1ml/12 gallon water. However they are asking not to use in new aquarium (less than 3 monts old) and the one with shrimps etc. Any suggestions? I am considering this because last night, upon a close inspection, I observed green threads in bunches on some plants as well as on my drift wood. Though I have cleaned it manually, It is bound to re-appear. I have also reduce some decor (lava rock) as I though it was interfering with proper water flow.
     
  17. Daniel Morris

    Daniel Morris Lifetime Charter Member
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    I'm intrigued by the discussion in this forum, and have found myself more 'homework' to do after looking at those links!

    If I may, I'd like to bring up the question that prompted me to look at this thread: Is pearling a continuous process?

    That is, given that the water column contains all the nutrients and CO2 that plants need to achieve their maximum uptake rate, would we expect the tank to begin pearling about 2 or 3 hours into the photoperiod and continue on until the lights turn off?

    If some plants grow faster and therefore pearl more than others, such as riccia, then lets assume the majority of the plants in the tank are fast growing plants such as Ludwigia repens, Heteranthera zosterifolia, Hemianthus micranthemoides, Hygrophila difformis, and Hygrophila corymbosa.

    The reason I ask this is because I only see pearling in the last 3 or 4 hours of my 10 hour photoperiod.

    Thanks-
    DM
     
  18. Frolicsome_Flora

    Frolicsome_Flora Guru Class Expert

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    since a period of stability, my plants pearl nicely after 1 hour of the lights going on, but it wasnt always the case.. for the first month or so of EI, it was only the last 3-4 hours.. it took a while for everything to get used to the higher co2/nutrients etc. That might not be the reason for your plants not pearling until later of course, but its something to think about.
     
  19. Tom Barr

    Tom Barr Founder
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    Well, big long chemical name, but you can tell right away, it's just a strong oxidizer...........

    Like peroxide, bleach, permangnate etc........these all kill algae and are dose dependent as well.

    Chlorine oxides.........

    You will never hear me suggest an algae killer other than perhaps Excel, but it helps plants growth via CO2 decomposition, rather than as a algae control, and since CO2 is a big issue with algae...........this is direct and indirect.

    So do not use the Tetra stuff.
    You are desperate and that is why such/those products sell.

    Instead, focus on CO2, pruning, water changes.
    Reduce the light intensity.
    Less light= less algae growth, less nutrient demand.

    Make sure the CO2 is in good shape the entire lighting cycle(not just one discrete point), by the sounds of the algae, that is the issue here.

    If you get desperate, use Excel at 5mls per 10 gal each day.
    A 3 day blackout with water changes each day + Excel will kill about any algae and be safe for all plants/shrimp.

    But you should alway focus on plant growth.
    Not doing that is why folks have algae.

    Cleaning well after moving things around etc is also very important, always do large water changes thereafter.

    Keep things clean etc and stay on top of things, then it'll be easy once things gte going well.

    Algae means you have slacked off on some routine/maintenance etc, so you do some extra work and whip things back into shape.

    Algae killers always market themselves as a silver bullet.
    There are no silver bullets other than good plant biomass/growth and matching the growth/nutrients with the lighting.

    In general, all algae killers also have a fitness penalty against the plants as well as the algae. So plants do not like them either and it hurts their growth......which is why you had algae to begin with. So they do not correct the root problem.
    Recall the old adage: correlation does not = causation.
    Algae killers and the entire theory relies on that for sales.
    Personally, I'd rather work with cause, otherwise you'd become dependent on algae killers and constantly have issues, but clearly I know of no successful plant folks that use algae killers as a routine.

    If you need to beat back algae while you correct the issues, you should correct those issues first and foremost.

    Then when you prune, clean, do a blackout, add Excel etc, you get the most out of the work. Otherwise you are wasting your time and effort.

    Regards,
    Tom Barr
     
  20. Tom Barr

    Tom Barr Founder
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    Well, some folks will see more pearling than others if the CO2/nutrients are the same and the plants species/biomass are the same as well.

    Can you guess why?
    What else besides CO2/nutrients cause plant growth?

    Lighting.........

    More light=> more growth= more CO2 demand= more NO3 demand/uptake/nutrients etc

    So with high light versus low light, which tank would pearl sooner and more intensely?

    The process of pearling is rate dependent, it is NOT, I repeat, NOT dependent on O2 saturation (Above 100% ambient O2 levels) in the tank's water.
    With fast growth, you have a large amount of O2 production inside the plant, this O2 is released via the stomata, lacunae etc and if the rate is high enough, O2 bubbles you can see are formed.

    If the rate is slow, then the bubbles are not visible/are readily dissolved into the water. Note, this is not really dependent on the tank's O2 level, you can and do get pearling at less than 100% O2.

    Less obviously will be dissolved in a tank with less O2, due to concentration differences, but you can easily have 150% O2 levels(well above 100%) and still have the gas going into solution.

    Saturation does not imply as much gas as the water can hold, it is only relative to the ambient conditions which is about 7-8ppm for most tanks. Water can hold a fair amount more O2 that 7-8ppm.......with or without pearling.

    Regards,
    Tom Barr
     
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