This site is supported by the advertisements on it, please disable your AdBlocker so we can continue to provide you with the quality content you expect.
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. We are after as many aquarium plant images that we can get, doing so will assist us in completing the aquarium plant database.

    https://barrreport.com/threads/aquatic-plant-images-wanted.14374/
    Dismiss Notice

Why heating cable do not work or various sized Grains, eg power sand

Discussion in 'Aquatic Microbiology' started by Tom Barr, May 28, 2008.

  1. Tom Barr

    Tom Barr Founder
    Staff Member Administrator

    Joined:
    Jan 23, 2005
    Messages:
    18,660
    Likes Received:
    600
    Local Time:
    5:03 PM
    This is a rather old paper and the plant is rather slow growing.
    However, the study was done well and details out the effects and issues surrounding aquatic plant roots and O2.

    Please read:
    http://www.plantphysiol.org/cgi/reprint/105/3/847.pdf

    Most of the proponents of heating cables or large pumice underlayments, "pseudo plenums" have suggested, and I might add........ without any evidence for support (if you have seen any real data, please contact me, because I've never seen any to date after looking for 20+ years)....that their products increase circulation and bring O2 to the anaerobic sediments below thereby enhancing plant root development/growth.

    It might help for aquarists to take a step back first and ask the question:
    What about the sediment that causes low O2 to begin with?

    1. There must be some organic carbon source in the sediment for aerobic bacteria to consume, otherwise the O2 levels will remain the same as the water column.
    This is obvious and testable, if there is nothing consuming O2 in the sediment, say plain sand, it does not matter how deep it is............the rate of consumption is essentially zero, so O2 can move in without being depleted.
    Typically, in a new aquarium, there is no organic matter in the sediment unless soil or ADA AS, and other amendments are added.

    2. Plants are not static, they will actively alter their environment. Aquatic plants are very well understood to act like "pipes", pumping O2 into the anoxic sediments. Given good light, CO2 and nutrients, they can do this amazingly well.
    This is natural process and needs no amplification. By adding O2 to the root zone, they effectively grow various species of bacteria that aid in the nutrient uptake and remove the need to add more circulation to the root zone.

    3. Algae are not limited by nutrients in the water column(Fe, NO3, PO4, K+), thus even if you ascribe to this theory, adding more circulation would conflict with this theory by allowing higher rates of nutrients to leach out.

    4. Grain size also plays a large role if any diffusion process in sediments. Over time, the grain size pore spaces are reduced and smaller grains migrate to the lower zones while large grains migrate to the top layer. Thus adding larger layers on the bottom will often not last over time. Pool and water sand filters use larger grains going to smaller grains from top to bottom as well for this very reason to aid in filtering. The sediment acts in a similar, although slower process, slowly clogging over time. Plants respond by adding O2 and growing more roots. The aquarist can deep vacuum once a year as well, or uproot and replant areas every few months, years as needed as well. Cables and other diffusion aids will increase the rate of clogging, not aid in plant growth.

    5. Are plant roots O2 limited to the point it limits growth in aquatic sediments?
    And if so, does adding flow, via cables or larger grains improve this in a significant way? These questions have never been answered.

    Read the article, think about aquatic plant roots, think about faster growing species in warmer temperatures and how that might affect the zone of O2 around plant roots, think about how a large sword plant or Crypt might influence the sediment with massive root systems, then remove the plant and predict what you might expect.

    By ignoring the plant roots' role in the process, as well as the pore size through time, it really appears to be based on marketing, not on plant growth or research.
    I talk to Claus from Tropica many years ago, as well as Troels and Ole recently about all this. They know of nothing that suggest the plants grow better using these two methods. Havign set up numerous aquariums with and without both methods, I've yet to see any evidence that they do as claimed.

    ADA's Power Sand appears to be a hold over from that time in history when the cables where popular, and the idea that adding nutrients to the root zone would limit algae. Dupla had already done 1/2 the marketing for you and PS is cheaper than cables. At least PS does add some nutrients.

    Still, nutrients can be added without the PS altogether.
    Thus we see no differences in growth without PS when the same nutrients are added back. Which mirrors the observations.

    More reading on this topic and N's role:

    Cookie Absent

    Archaea Dominate the Ammonia-Oxidizing Community in the Rhizosphere of the Freshwater Macrophyte Littorella uniflora -- Herrmann et al. 74 (10): 3279 -- Applied and Environmental Microbiology



    Regards,
    Tom Barr
     
  2. paludarium

    paludarium Guest

    Local Time:
    11:03 AM
    Hi Tom,

    I'd like cite your words for those who are still pondering the usage of bottom filters. Dupla promoted heating cable in two ways: to increase circulation in the sediments; and to eliminate the "cold feet" of the aquatic plants or to provide the warm enviroment in the sediments, especially in the winter. Neither plants nor bacteria loves cold enviroments, and both grow better in higher temperature. Maybe this was why some people declared that plants grow better when using heating cable.

    BTW, I am confused wtih the results in this research Archaea Dominate the Ammonia-Oxidizing Community in the Rhizosphere of the Freshwater Macrophyte Littorella uniflora -- Herrmann et al. 74 (10): 3279 -- Applied and Environmental Microbiology. Does that mean Archaea dominate the ammonia oxidizing process in the rhizosphere but not bacteria? Or AOA only live in the enviroment with high O2 levels especially near roots zone, but not in the filter? And what about the leaves and the stems of the aquatic plants?

    Regards,
    Erich
     
  3. Tom Barr

    Tom Barr Founder
    Staff Member Administrator

    Joined:
    Jan 23, 2005
    Messages:
    18,660
    Likes Received:
    600
    Local Time:
    5:03 PM
    I would agree with this assessment far far more, than any of the claims from Dupla or their "believers" cult. Also, we know warmer temps increase growth, cycling rates etc. So a subtle increase in temp is the real factor for any differences(if there are any, which itself is debatable in and of itself).

    So yes, I buy your view on this.
    It's one possibility and that would need to adressed to show that circulation, or that O2 etc is the real reason. Still, if a warm feet is all we need, a simple reptile heater on the outside or simply keeping the tank warmer, RFUG's(something I used to keep the same temp in the water column and sediment........too address the claims about "cold feet"). I did this as well.
    For well over a decade with RFUG's and plants.

    Bacteria will live in zones, dominated by flow rates through them, and Redox levels/O2 levels. So some might live at say 300mv, others, might do well at 150mv, and others yet might do best at 50mv Redox level.

    Yes, in terms of NH4 oxidation, it would appear that the Archaea are doing most of the work there according to this article. In other plants, the roots might also increase the removal rates due to uptake by the plant roots etc. This is a slow growing plant that invest a lot into the roots vs fast growth.

    Still, the plant:bacterial linkage is likely stronger than many assume in aquatic sediments.

    Regards,
    Tom Barr
     
  4. neil1973

    neil1973 Prolific Poster

    Joined:
    Dec 17, 2005
    Messages:
    58
    Likes Received:
    0
    Local Time:
    5:03 PM
    I don’t buy the whole heating cable / nutrient circulation thing either and don’t use them in my tank. However I have often wondered about the temperature of the substrate and the effect that might have on enzyme activity etc in the roots. I live in Scotland and at this time of year it’s not warm. The tank is in the living room but that only gets heated when someone is there which is often for just 4 – 5 hours in the evening. The room probably gets down to 10 – 15C for considerable periods so I can imagine that in the lower portions of the substrate it’s not too warm. I haven’t tried to measure the difference but stuck my finger in the substrate and it does feel cold :) . I guess that in tanks with some form of bottom heating the substrate could actually be warmer than the water column so I’m guessing the difference in substrate temps in a tank like that and a tank like mine could be 10C or so. Don’t know what the Q10 for enzymes in aquatic plant roots is, or whether just the lower root portion of the plant being cold when the rest is warm is significant, but It might be enough to explain any changes in growth that people think they see in relation to bottom heating. I’m not sure when the whole substrate heating idea started but I think it was 30 odd years ago in Europe. The average European house back then was probably significantly colder than those today and those in the US. So perhaps people where benefiting from the warmer temps.

    All this said my plants seem to do fine with the colder substrate. Perhaps if I ever strip the tank down for any reason I’ll try a reptile mat like Tom suggested, or I could just move somewhere warm :)

    Cheers
    Neil
     
Loading...

Share This Page