So what is organic wastes?

Discussion in 'Water Chemistry' started by jameson_uk, 29 Aug 2017.

  1. jameson_uk

    jameson_uk Member

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    I am often come across things that say x species is intolerant of organic wastes or you should avoid a build up or organic wastes but this got me thinking as to what they actually were

    I guess I have only really though about waste in terms of the nitrogen cycle and when a fish poops or leaf decays that breaks down to ammonia => nitrite => nitrate...

    Are organic wastes just anything containing carbon and if so does that really just mean poop and dead flora / fauna?

    Evolution Aqua Pure says it contains Heterotrophic bacteria which consumes organic wastes but presumably as leaves decompose in your tank normally I guess these or similar must be present in the tank anyway?

    So given flora, fauna and poop all decompose in the tank, what is it that builds up or is actually bad? I guess decomposition will consume oxygen so reduce the amount available for fish, plants and nitrification bacteria but this could be counteracted by more surface agitation to keep oxygen levels up?

    What am I missing?
     
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  2. zozo

    zozo Member

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    :thumbup:

    Next to what you guessed correctly, to much organic waste can become toxic and even pathogenic.
     
  3. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    Hello,
    Organic waste, such as food, poop, urine as well as the waste products excreted by plants, is deadly because bacteria continue to feed and break down these components. The bacteria that perform these functions are aerobic, meaning that they are oxygen breathers. In so doing, therefore, they steal oxygen from your fish and from your plants, leaving the fauna more susceptible to pathogens and leaving the flora more susceptible to algal attacks.

    This is the main reason for the advocacy of frequent and large water changes.

    Cheers,
     
  4. jameson_uk

    jameson_uk Member

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    So this is where I appear to be struggling....
    If someone said a fish needed highly oxygenated water I can understand that but not being intolerant of organic wastes.

    On top of that there appears to be a lot of people advocating not vacuuming the substrate. Poop, food and plant leaves etc. will tend towards the substrate and when breaking down will provide nutrients (particularly for root feeders?). Just changing the water will mainly remove what has dissolved into the water column which means the bacteria has already broken the waste down?

    Given people add lead litter (which I guess is technically organic waste) then like everything else I am assuming this is just a balancing act.
     
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  5. roadmaster

    roadmaster Member

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    Easier to remove regularly the solids, dissolved waste's,through water changes,reg maint, than trying to find a perceived balance .
     
  6. ian_m

    ian_m Global Moderator Staff Member

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    Yes the organic waste will rot down to plant food BUT only in low light low tech tanks. This is why some people can go for ever without changing tank water.

    In high tech high light tanks the waste is produce too fast for natural processes to harmlessly rot it away to plant food, thus water changes are required.
     
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  7. zozo

    zozo Member

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    It's the small closed invironment which can turn it into a problem if water changes are left out.. Even tho you have flow and a filter, without water changes even with 1m³ water, it is still a closed system. Tolerance and intolerance is very relative and differs enormously among fish sp.. Take for example a Carp, one of the strongest fish around can survive highly eutrophic waters very low in oxygene and rich in organic accumulations and infested with parasites. They are about the last fish to die in such invironments. The Eel is even more resiliant, it literaly lives in organic waste, digs into it and even can survive drouth periods in damp soils. Other fish sp. are highly senstive to polutions or off values like low oxygene. These sp. are used for that by pond owners as indicator sp. A certain kind of Minnow.. I they die, you need to do some checking because there is some sh*t about to hit the fan. And kill everything else if nothing is done.

    Anyway an aquarium without water changes is very unnatural.. It doesn't occure in nature, even what we perceive or describe as stagnant bobies of water, actualy are not realy absolute stagnant.. Flow is just a neglectable minimal, not worth mentioning. Real natural stagnant bobies of water are never permanent, only get created after flooding, so if flooding stops and retracts it leaves behind a stagnant pool, but if it is no longer fed with new water. It will slowly drain or evaporate and dry out. (We get our aquarium fish from a lot of these stagnant jungle pools after the flooding periode.)

    So every permanent body of water you perceive as stagnant, isn't realy stagnant, it is fed with fresh water from one or several places and it also drains at other places. It must have logicaly or else it can't permenantly excist. :) It needs a constant or regular fresh water supply for that and find a healthy balance if it doesn't have it can only accumulate and never flush anything out.. And that is excactly what happens in a fish tank without water changes.. It accumulates, it's a matter of time, not if but when it runs out of control.
     
    Last edited: 12 Sep 2017
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  8. roadmaster

    roadmaster Member

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    I believe given the number's of people who place fishes in their planted affair's,and number's of people who over feed,that the waste from fish food's, and fish poo ,will be primary source of organic waste in closed system mentioned.
    Some overfeed more than other's might.have more fauna or less,(balance would be different/fleeting/fluid situation truly)
    Would be hard to nail down a balance that might change weekly assuming good plant growth.(more growth,more nutrient's consumed)
    We hope decaying plant matter is not produced in excess, lest it indicate something is missing for plant's to do so poorly..
    Other's keep plant only tanks and plant's rely on hobbyist to provide primary source of food/nutrient's along with maybe a little from substrates.
    Not as much organic matter created sans fauna.
    These are some thing's I have observed in low tech NON CO tanks.
    Swap over to high tech,higher light energy, and everything is accelerated, due to more light energy driving plant/fish metabolisim's.
    Must be some export mechanisim in closed loop, in addition to plant uptake when everything is running at eleven to keep both plant's and fishes happy.IMHO
     
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  9. dw1305

    dw1305 Expert

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    Hi all,
    The real answer is that not all organic wastes are the same.

    Dissolved organic carbon compounds (DOC) can be used as a marker of pollution, and the "water" flowing from a landfill, out of a silage clamp or into a sewage works, would be highly polluted with a high BOD (Biochemical Oxygen Demand), high DOC and high TSS (Total Suspended Solids), but these parameters don't necessarily have to occur together.

    This is 50% diluted landfill leachate and gives you an idea of how tinted the full strength leachate is

    Lemna50%.jpg
    Yes, the reason that all DOC isn't equal is that, while all life is carbon based, plants also use complex carbohydrates for their structural support. Dead tree leaves, (or bark and wood) are very slow to degrade, because they don't have any of the easily decomposable sugars and proteins, just complex carbon compounds (cellulose, lignin, humic and phenolic compounds) that are resistant to decay. This is why scientists use BOD as a measure of pollution, it can differentiate between easily oxidisable compounds (these have a high BOD) and structural carbohydrates (these have a low BOD).

    In a highly oxygenated, base rich, situation, even if it is nitrogen poor (like the upper layers of lake Tanganyika), the water will have a high degree of clarity, because any dissolved organic carbon compounds (DOC) will oxidise away via microbial action, also a large suite of invertebrates ("detrivores", snails, shrimps etc) will clean up any dead leaves etc. Lake Tanganyika cichlids are often said to be "intolerant of organic wastes", and have evolved in an environment where they are only present at very low levels.

    You can also have water that is very nitrogen poor with a high level of DOC, usually because conditions are nitrogen poor, acidic and low in oxygen, and these are the conditions that peat forms under in NW Britain. Water flowing through peat (or a stream rich in leaf litter) will pick up DOC and become "black-water", but it will still be low in nutrients and have a low BOD.

    cheers Darrel
     
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  10. jameson_uk

    jameson_uk Member

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    So one thing that still confuses me is the D... to become dissolved the decomposition has to have already occurred? If that is the case then the oxygen used by the bacteria to break down the solids would have already been used?

    So for Lake Tanganyika cichlids (and presumably Rainbowfish from fast flowing rivers in Papa New Guinea) the intolerance is actually the level of DOC rather than the need for high levels of oxygen? The fish might be happier in a sterile tank with some surface agitation than in a heavily planted tank with lots of oxygenation but but lots of poo and decaying plants?
     
  11. techfool

    techfool Member

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    urea, fish slime, fish scales, hormones, skin cells, mucus, proteins, rotting food and leaves, stuff like that?
     
  12. zozo

    zozo Member

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    I think you kinda misinterpreted dissolved and size, in organic waste.. Take for example Urine which is an organic waste same as a solid turd is, but fluid instead. Fish also secrete fluids containing Ammonia.. Since it is fluid everything in there seems dissolved, it is, but it still is a non processed toxic organic waste and it needs that nitrification cycle before it's contents is converted from amonia into nitrates etc.

    http://www.differencebetween.com/difference-between-urea-and-vs-urine/
     
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  13. AverageWhiteBloke

    AverageWhiteBloke Member

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    V Interesting discussion, most people assume I guess that anything inside the aquarium will be at some point at one of the stages of the nitrogen cycle and eventually be turned into something else and ultimately degassed as nitrogen or consumed by the plants. Obviously there are further things in there that no amount of filtration or healthy plants could deal with. I think it would be beneficial to members to have a list of what these components are, maybe that would save a lot of confusion over the necessity of the water change if people could say or think they were removing x and not resetting etc.

    In the same vein I have often wondered where the plants fit into this? We are often told when growing plants at high rates of growth under high lighting that the plants are also net contributors to the amount of waste in the tank. In which way do the plants contribute to waste levels when it is often said the plants are consuming the waste?
     
  14. zozo

    zozo Member

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    Next to the obvious sheding/melting dead plant material, a living plants consumes, builds and again secretes such as Oils and proteins, which are partialy again waste products. That famous often discussed surface biofilm is often caused by plant secretion.
     
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  15. zozo

    zozo Member

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    Maybe the best obvious example of plant secretion we all witness now and then is smelling plants.. Take for example Basil, the air movement from only walking by makes it's leaves brush together and is enough to make it release a load of volatile chemicals. The various essential oils you can buy in the healthshops etc, also contain these volatile chemicals. These are distiled from plantmaterial and concentrated.

    These chemicals are released into the atmosphere and you smell it. In an aquarium we also have an atmosphere, but as closed invironment with an steady X volume of water rather a very tiny atmosphere. It has no where else to go, so it all accumulates.

    Not all plants smell for us, but it doesn't say they do not release these chemicals among others. I remember Rotala mexicana Goyas, that is a real stinker, smells awfull this little bugger. :)
     
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  16. dw1305

    dw1305 Expert

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    Hi all,
    It is like the others have said, a variety of compounds will be leaking from dead (and living) organisms all the time.

    If we ignore growing plants for a moment, all the easily decomposable metabolites (lipids, ammonia, sugars, proteins) will be rapidly taken up and will fuel microbial growth, depleting oxygen. What is left, after these low hanging fruit have gone, will be the structural carbohydrates, chitin, snail shell etc. which aren't easily broken down and will slowly accumulate.

    This also includes the poo you can see, it is fairly inert. Fish don't urinate, as such, either, but ammonia continually diffuses from the fishes gills, you can't see it, but it is the real danger.
    No, plants are the easiest way of maintaining high water quality, they are massively net consumers of nutrients (including CO2) and suppliers of oxygen.

    You can use large water changes to maintain water quality, in the same way that you can rely on microbial biological filtration, but water changes combined with plant/microbe filtration is a safer option.

    Some recent research suggests that even the low levels of DOC in "clear water", like sea water, Lake Tanganyika etc. may be important in maintaining fish health. There are references in <"How to remove.....">.

    cheers Darrel
     
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  17. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

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    It appears that the term "Dissolved Solid" is unclear to many. My guess is that folks often assume that if a solid object, like a sugar cube, is dissolved in a cup of tea, then it's no longer a solid. Of course, it can't be seen so it must not be a solid anymore, it must be a liquid.

    if this is the source of confusion, then it is a fundamental misunderstanding.
    Have a look at this video:



    You can see that the electrical properties of water causes "disassociation" of the components that comprise the solid, but the salt is still a solid.
    If you boil the water off the salt will re-appear.
    In order for the salt to be come a liquid, you would have to continue heating it to about 800 degrees C. At that temperature there will be a fundamentl change in the relationship between neighboring atoms that comprise the salt.

    It is a similar story with organic proteins and waste molecules. They are considered "dissolved" because the water molecules surround the molecules in a similar fashion.

    Bacteria then seek out the molecules and break them apart by chemical means. The oxygen molecules, which are themselves dissolved (and surrounded) in exactly the same way, are also captured by the bacteria and used in the chemical attack upon the solids.

    By this method, dissolved gaseous Oxygen is removed from the water and the dissolved solids which are comprised of Nitrogen, Phosphorous, Carbon and other important elements are eaten by the bacteria.

    So the answer is NO the breakdown starts once the solids are dissolved, not before.
    The the one thing most important to fish is dissolved Oxygen, because Oxygen is very poorly dissolved in water and is therefore always is short supply.

    DOC robs the water of Oxygen, so having lots of decaying plant matter and other organic sources is not good. That's why you need to change the tank water as often and as much as feasible, to rid the tank of DOC. This is always going to be true even in your so-called "sterile tank" - and of course this is inaccurate anyway because there will never be any sterile tank, because it will have poop, urine, and uneaten food in it anyway and will require water changes.

    In any tank, the imperative will always be to remove DOC, but in a planted tank, which enhances the dissolved Oxygen content by way of photosynthesis, it provides a wider margin of error. Plants also foster the development of aerobic bacteria in the sediment and they oxygenate the sediment as well by manufacturing Oxygen and passing that Oxygen down to the roots. The bacterial chain in the sediment is enhanced and toxins are removed in the sediment in the same way they are removed in the water column and in the filter. So toxic substances from the sediment are less likely to leach into the water column.

    Cheers,
     
  18. Daveslaney

    Daveslaney Member

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    Really interesting thread this,So my guess is proberbly the biggest contributor to DOC in your tank is dirty mechanical filter media in your canister filter?
    It is designed to macanically trap waste before it enters the bio stages, But being in a higher pressure envioment the rate it dissolves this waste into the water will be greater? Happen quicker?
     
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  19. roadmaster

    roadmaster Member

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    Biggest contributor is the waste from fish food's,fish poo,decaying plant matter , which in turn can contribute to dirty filter material.
    Hard to have the latter without the former.
    Is of little consequence with weekly water changes and regular filter maint. IMHO
     
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  20. dw1305

    dw1305 Expert

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    Hi all,
    The mechanical filtration media will trap particles, how small those particles are will depend on the pore size of the filter material, but these are solid objects, rather than being dissolved.

    A really fine mechanical filter (diatomaceous earth etc), or a chemical media like "Purigen", will also trap colloids, unicellular algae and very fine suspended solids and this will "polish" the water.

    If you have fish food, faeces etc. trapped in the mechanical media some of the more soluble, or easily decomposable, compounds, will enter the water column as DOC or ions, with the remnant left as the ash and structural carbohydrates etc. that don't biodegrade, or are only slowly degraded. The microbial part of the decomposition is dependent upon there being enough oxygen.

    We would really like to know both the Biochemical Oxygen Demand (BOD), and dissolved oxygen (%DO) content of our tank water, but they aren't easy to measure.

    But if you can get enough oxygen into the water you can process wastes with a huge BOD, this is how the <"activated sludge" process works in waste water treatment">.

    Because we can't get a direct measure of oxygen levels, or BOD, I like techniques that maximise the amount of oxygen in the water, the reason for this is that as long as you have a lot of oxygen, you can deal with a lot of BOD.

    The easiest ways of getting a lot of oxygen in the water are to have growing plants and a very large gas exchange area to water volume ratio.

    If you have a wet and dry trickle filter, or even better a planted wet and dry trickle filter, you have a system that can deal with a huge volume of organic waste, both dissolved and solid (it has a huge gas exchange surface and is extremely difficult to clog).

    If you have a canister filter it a sealed vessel, and a finite amount of oxygen enters the filter.

    If you have your mechanical filtration inside the filter, and use your filter as a siphon (for example if you have floss and don't replace it as frequently as you should) then you run the risk that the biological media will become anaerobic and nitrification will cease, leading to the filter ejecting a stream of de-oxygenated, ammonia rich water.

    If you have a planted tank with substrate even this may not prove disastrous, because you have the "belt and braces" of the plants (which produce oxygen and take up ammonia (as NH4+)) and substrate (where nitrification will occur), but if you are entirely reliant on biological filtration in the filter it is game over.

    cheers Darrel
     
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