Do Healthy Plants Release Organics?

Discussion in 'Water Chemistry' started by jaypeecee, 28 Nov 2019.

  1. jaypeecee

    jaypeecee Member

    Joined:
    21 Jan 2015
    Messages:
    552
    Location:
    Berkshire
    Hi Folks,

    I am trying to get a full(er) picture of what contributes to dissolved organic carbon (DOC) in freshwater aquariums. Why? Well, I still have an ongoing problem with an oily film on the water surface. Using the kitchen paper towel method is effective but the result is short-lived. I syphon the substrate, I don't over-feed my fish and I use organic waste removal media in my external filter. The filter is cleaned monthly. If all else fails, I'll resort to a surface skimmer but I'd rather deal with the root cause.

    Unhealthy, decomposing plants will obviously contribute to DOC. I do believe that healthy plants must also contribute to DOC. Otherwise, I presume that allelopathy couldn't occur. So, do healthy plants release organics (into the water column)? And, would this be sufficient to contribute to the formation of surface films?

    JPC
     
    Last edited: 28 Nov 2019
  2. Edvet

    Edvet Forum Moderator Staff Member

    Joined:
    15 Aug 2013
    Messages:
    5,149
    Location:
    Lelystad, Netherlands
    Which? and why?
     
  3. dw1305

    dw1305 Expert

    Joined:
    7 Apr 2008
    Messages:
    9,357
    Location:
    nr Bath
    Hi all,
    I think they do, plants are generally pretty leaky structures.

    Somewhere there is a <"more thorough post, than this one">* by Clive @ceg4048, or Tom Barr @plantbrain, that says the reason for the 50% water change when you use EI is as much to remove DOC as to remove any excess of ions.
    Edit: * Possibly this one <"Water flow......">

    cheers Darrel
     
    Tim Harrison and Zeus. like this.
  4. Fisher2007

    Fisher2007 Member

    Joined:
    19 Feb 2018
    Messages:
    380
    Location:
    Warrington
    What foods are you feeding?

    Until recently I ran two planted low tech tanks and didn't struggle with oily film. Neither had a surface skimmer

    In my first marine system I used to suffer from an oily film though. This tank didn't have a sump and so the surface wasn't being skimmer via the outlet/downpipes. I did have a protein skimmer though and probably 25x plus turnover as well but even then this still didn't help. What I did notice though was depending on what I fed it influenced the amount and density of the film, with frozen foods being the worst for it, hence the question
     
    dw1305 likes this.
  5. dw1305

    dw1305 Expert

    Joined:
    7 Apr 2008
    Messages:
    9,357
    Location:
    nr Bath
    Hi all,
    I think certain foods have this effect. I mainly feed live food and very rarely have any surface film.

    cheers Darrel
     
  6. jaypeecee

    jaypeecee Member

    Joined:
    21 Jan 2015
    Messages:
    552
    Location:
    Berkshire
    Thanks, everyone. Some very useful feedback there - especially about the types of food to feed. As a result of your feedback, I'm going to dig into the feeding thing in more detail. In the first instance, I'll check the composition of the foods that I currently use. Currently, I'm not feeding any live foods. The nearest I get to that is frozen bloodworm. Almost 100% of what I feed comes out of a tub. For example, Bug Bites, Seachem flakes and TMC Gamma pellets. @dw1305, would I be right in thinking that you probably feed Daphnia? And thanks for the comment about plants being "generally pretty leaky structures". Plus, the statement that "the reason for the 50% water change when you use EI is as much to remove DOC as to remove any excess of ions".

    JPC
     
  7. dw1305

    dw1305 Expert

    Joined:
    7 Apr 2008
    Messages:
    9,357
    Location:
    nr Bath
    Hi all,
    Mainly Daphnia, Grindal worms and Micro worms with some Black worms, Crangonyx, Aphids and Sciarid flies at the moment. In the summer there would be a bit more variety with Mosquito larvae and Blood worms added in. In amongst the Daphnia there would be some Copepods and Ostracods.

    I usually have a vestigial winged fruit fly culture as well, but I don't have one at the moment (hence the Aphids and Sciarid flies).

    Dried food I've got "Freeze Dried Arctic Copepods" and "TA Blend no.1" from <"TA Aquaculture">. I might try the <"Artemisia Soft Pellet"> next time I buy some dry food.

    cheers Darrel
     
  8. jaypeecee

    jaypeecee Member

    Joined:
    21 Jan 2015
    Messages:
    552
    Location:
    Berkshire
    @dw1305 - lucky fish! BTW, the link to TA Aquaculture is handy. You may also be interested in https://www.zmsystems.co.uk.

    JPC
     
    Last edited: 29 Nov 2019
  9. dw1305

    dw1305 Expert

    Joined:
    7 Apr 2008
    Messages:
    9,357
    Location:
    nr Bath
    Hi all,
    Yes, that is the one that the University use when they work with Zebra "Fish" (Danio rerio), I'm not sure I can afford them.
    I don't get through much dry food, but I've traditionally bought my food from them.

    Tim (Addis) has a Facebook page as well, that is where the link to this video came from.



    cheers Darrel
     
    jaypeecee and Geoffrey Rea like this.
  10. Iain Sutherland

    Iain Sutherland Forum Moderator Staff Member

    Joined:
    7 Jul 2011
    Messages:
    3,675
    Location:
    Cambridge
    Im yet to see or keep a high tech tank that doesnt have a surface film. If you look at ADA gallery, Green aqua gallery, aquarium gardens or any high end outlet that keep multiple tanks to see that every tank runs a surface skimmer of some kind. Obviously tanks that run overflow systems are excluded from this.

    Low tech it really isnt an issue (aside high feeding levels and poor maintenance) but put high energy on a tank and DOC increases to a point that surface agitation doesnt seem to cut it.
     
    dw1305, jaypeecee and Tim Harrison like this.
  11. Tim Harrison

    Tim Harrison Super Moderator Staff Member

    Joined:
    5 Nov 2011
    Messages:
    7,288
    Location:
    Leicester
    It's pretty much a fact of life with planted tanks, healthy or otherwise. I once had a surface film as thick as treacle in a newly planted tank. Even strong surface movement did little to disperse it, it all just wrinkled up at one end like Nora Battey's tights. Other than that the tank was a great success, so it's not necessarily a sign that something is wrong...

    Just get one of these...

    upload_2019-11-29_18-38-30.jpeg
     
    jaypeecee and John S like this.
  12. jaypeecee

    jaypeecee Member

    Joined:
    21 Jan 2015
    Messages:
    552
    Location:
    Berkshire
    Hi @Iain Sutherland

    That's really useful feedback. Combining the comment by @dw1305 that "plants are generally pretty leaky structures" with your statement above, I conclude that, in the 'high tech' environment, it is most likely the plants that are causing the surface film. If that's the case, then the surface film cannot be prevented - or can it? (see my next post). Thus, the only option is to do what @Tim Harrison is suggesting, i.e. use a surface skimmer. As it happens, I have ordered an Eheim skim 350, which should arrive today.

    JPC
     
    Last edited: 30 Nov 2019
  13. jaypeecee

    jaypeecee Member

    Joined:
    21 Jan 2015
    Messages:
    552
    Location:
    Berkshire
    Hi Folks,

    If the root cause of the surface film is DOC produced by the plants, is it not possible to use activated carbon, Seachem Purigen, etc. in an external filter to remove these dissolved organics? Surely, that ought to be a possibility? I would have preferred this approach in order to eliminate another piece of equipment inside the tank itself. I consider the surface skimmer to be a last resort. I don't think dissolved organics get enough attention on freshwater aquarium forums/fora.

    JPC
     
    Last edited: 30 Nov 2019
  14. dw1305

    dw1305 Expert

    Joined:
    7 Apr 2008
    Messages:
    9,357
    Location:
    nr Bath
    Hi all,
    I think the issue is probably the lipid and wax component, it floats and will combine (both physically and chemically) with <"proteins, complex carbohydrates etc">. This layer then supports bacteria, fungi etc.

    This surface dwelling microscopic community has a scientific name, it is the "neuston".

    I think the main issue is that it would only need a small amount of lipids to cover the entire water surface, in a one molecule thick layer. You can't set the intake of a conventional filter to skim the surface, the filter will fill up with air, and protein skimmers don't really work in freshwater (it isn't dense enough), so that really just leaves a surface skimmer as an option, if you don't have a weir/sump setup.

    I've never really suffered from it, but all my tanks have Tadpole and Ramshorn snails which are often "surf", between the floating plants, and may consume the surface layer quickly enough so that it never becomes too visible. The mechanism for Apple Snails feeding on the surface film is called "pedal surface collecting", but I don't know if smaller snails have the same adaptations.

    cheers Darrel
     
    jaypeecee, Oldguy and Tim Harrison like this.
  15. MJQMJQ

    MJQMJQ Member

    Joined:
    11 Nov 2019
    Messages:
    243
    Location:
    SIngapore
    Yep darrel is right.DOC will stain the water darker and is released by decaying organics.Plants need the carbon to grow so Im guessing it will not release it into the water.Prob to do with excess lipid production temperatures can also affect these things.Different species also have varying production.From what I know terrestrial species produce root exudates to form beneficial relations with fungi and bacteria.
     
  16. MJQMJQ

    MJQMJQ Member

    Joined:
    11 Nov 2019
    Messages:
    243
    Location:
    SIngapore
    Well I like to think that they are selectively leaky to benefit themselves eg releasing co2 during respiration as byproduct because they dont need it clogging up their transport system.Its like say u can transport only 1000 units of goods, would u choose to transport co2 if it is useless and u need oxygen?
     
  17. jaypeecee

    jaypeecee Member

    Joined:
    21 Jan 2015
    Messages:
    552
    Location:
    Berkshire
    Hi Folks,

    I installed my new Eheim skim 350 today and it has now been running for several hours. It has made an improvement but there still appears to be a thin oily layer on the water surface. Having thought about how this surface skimmer works, I can't see how it can be fully effective. The sponge inside the skimmer has a coarse structure. I would estimate the 'pore' size to be about 1mm. It is just a simple, tiny synthetic sponge with no obvious impregnation. How can such simple filtration media trap anything other than particulate matter? Wouldn't carbon-impregnated foam be a better choice? I guess it would still need to be a coarse foam so as not to impair the suction.

    JPC
     
    Last edited: 30 Nov 2019
  18. MJQMJQ

    MJQMJQ Member

    Joined:
    11 Nov 2019
    Messages:
    243
    Location:
    SIngapore
    Yep activated carbon impregnated foam or polyurethane foam will absorb the oils.It works by absorbing them.Is the foam polyurethane foam?
     
  19. dw1305

    dw1305 Expert

    Joined:
    7 Apr 2008
    Messages:
    9,357
    Location:
    nr Bath
    Hi all,
    Yes, they need dissolved gases and ions to pass in and out of the plant through the epidermis. Even though a lot of aquatic plants don't have stomata they are still leaky structures.
    Yes, research (a lot of it on Rice) has shown In roots the plant can change the composition of the exudates to manipulate the biotic and abiotic environment in the rhizosphere.
    The CO2 is never actually a waste product, even when there is an excess of it during the dark period. Plants are very good at sequestering both the spare oxygen from photosynthesis and the CO2 respiration for use in the reciprocal process.

    Plants are actually much more interested in removing "waste" oxygen, there are two reasons for this, one is that high levels of oxygen inhibit photosynthesis, and the other is that plants are massively net oxygen producers. One molecule of oxygen is evolved for every molecule of CO2 incorporated during photosynthesis, but plants are carbon based and their growth records that difference between CO2 incorporated and evolved.

    cheers Darrel
     
    Zeus. likes this.
  20. Oldguy

    Oldguy Member

    Joined:
    27 Aug 2018
    Messages:
    350
    Location:
    Gloucestershire, UK
    Some very interesting information and opinions on this thread. I have found the effectiveness or otherwise of a surface skimmer to be related to surface area proportions. In general if the tank is linear/rectangular and long form, skimmers are less effective that if the surface is square. I use a very under powered a.n.other skimmer to great effect with a cubic tank.

    The coarseness of the filter material was at first disconcerting but I think its the biofilm that grows on the media that does the work and not mechanical filtration.

    As to the origin of the film I would suggest lipids** from the plants and from flake food. These as at @dw1305 entrap proteins and feed microorganisms.

    In natural waters you can see snails grazing the the under surface of the water. I also seem to remember guppies and sword-tails vaccing the water surface.

    In natural waters dull films are considered natural* and refractive films are considered to be hydrocarbons from run off.

    * Not that natural when heavy rains have caused septic tanks to overflow into no perceptible flow watercourses. It can also occur from vegetable cooking oils** again from septic tank overflows.
     
    Last edited: 1 Dec 2019
    jaypeecee and dw1305 like this.
Tags:

Share This Page

Facebook Page
Twitter Page
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice