Do Healthy Plants Release Organics?

[jaypeecee]

Just an observation, Otos et al are often very busy on plant leaves that are strong, healthy and have no obvious algae.

Hi @Oldguy

This is something I've noticed many times and been intrigued by it. Yesterday, I was chatting with an ichthyologist who confirmed what I had long suspected, which is that Otos (and others) feed on something known as periphyton. Please take a look at:

https://en.wikipedia.org/wiki/Periphyton

We, as aquarists, would probably refer to this as biofilm. But, according to Wikipedia, biofilms can take many forms - including dental plaque! If interested, please see below:

https://en.wikipedia.org/wiki/Biofilm

And it's now an even wetter, rainy day.

JPC

 

[Oldguy]

aquarists, would probably refer to this as biofilm

Good evening @jaypeecee, Thank you for your links, most interesting. Nothing in life is good or bad. I rely of biofilm [hopefully the good guys] in my wet/dry trickle filter which I modeled on a sewerage works treatment plant as a important part of my tank set up.

Complex films of chemicals, bacteria, protozoa, rotifers and fungi are intriguing. As a young lad I fell in love with rotifers and spent many hours looking into bird-bath films with a pocket microscope, much to the chagrin of some of my teachers and the wry support of my headteacher who could not make me out but gave much support.

Keeping fish in a planted tank brings all branches of science together with a wealth of practical observation and application. We learn new things every day, long may it continue.

 

[dw1305]

Hi all,

Yesterday, I was chatting with an ichthyologist who confirmed what I had long suspected, which is that Otos (and others) feed on something known as periphyton.

I'm a <"periphyton fan"> as well.

There is quite a lot of discussion of <"periphyton, aufwuchs"> etc on PlanetCatfish, where a lot of the Loricariid catfish are <"specialised aufwuchs"> feeders.

cheers Darrel

 

[jon32]

Hi, Interesting thread. I can rule out fish food as my 60X30X18 high tech tank always has surface film. The tank only has a few cherry shrimp and is heavily planted. I don't feed the shrimp I just leave alone to graze on the biofilm.

 

[jaypeecee]

Hi Folks,

I very recently stumbled across this post:

https://www.ukaps.org/forum/threads...d-about-bacteria-in-filter.28795/#post-299821

Note the comment that "plants produce a LOT of waste, especially if the tank is enriched with CO2 via gas or liquid". So, does this not support the idea of continuously removing DOCs using suitable filtration media such as Seachem Purigen? Is this what other UKAPS members do?

JPC

 

[zozo]

Plants do release / respirate a lot of organics, think of smell for example to attract pollinators or to repel predators.

Think of the good-smelling essential oils, people extract from all kinds of plants and put it concentrated in a bottle.

It's this stuff that is a building block from the oily biofilm scum layer we sometimes see on the water surface in our aquariums.

 

[dw1305]

Hi all,

Note the comment that "plants produce a LOT of waste, especially if the tank is enriched with CO2 via gas or liquid"

That is part of the reason for the big water change in EI and why people run surface skimmers, overflows etc. Marine reef aquarists use <"protein skimmers">, but these don't really work in freshwater.

So, does this not support the idea of continuously removing DOCs using suitable filtration media such as Seachem Purigen?

In terms of the "Purigen" it is back to the <"size of the particles"> it removes. In terms of large non-dissolved particles and fine mechanical filtration, you just need to ensure that you change the filter media over really frequently to avoid clogging.

The answer to a lot of these questions is really to do with oxygen, natural systems low in DOC tend to be <"nutrient poor, highly oxygenated and with alkaline water">. As you move away from these scenarios (or look at the wider picture) then the situation becomes <"more complicated">.

In terms of DOC generally, it is an entirely natural component of all aquatic systems, just in differing amounts. Is there any advantage to its complete removal, I'm pretty sure that answer is "no", and that if you could get water entirely devoid of DOC it would impinge on fish health. There is quite a lot of <"scientific research in this area">, although @jaypeecee may not like the <"shades of grey"> aspect to it.

Personally I think that the <"BOD concept"> is more useful, which is why you <"can have tanks full of structural leaf litter and dead wood">, but with very high water quality.

cheers Darrel

 

[Witcher]

you <"can have tanks full of structural leaf litter and dead wood">, but with very high water quality.

Not to mention that dead leaves/wood is a source of cellulose which is absolutely necessary for many sucker fish (Ottos etc.). Can't find sources now but it's related with the health of their digestive system.

 

[jaypeecee]

...although @jaypeecee may not like the <"shades of grey"> aspect to it.

Hi Darrel...you've got me sussed.

JPC

 

[jaypeecee]

In terms of the "Purigen" it is back to the <"size of the particles"> it removes.

Hi Darrel,

My concern is not about particulate matter - that's easy to remove with mechanical filtration. Let's go back to the start - surface film. As surface film appears to be caused by dissolved organics, then how do we remove these organics? Isn't this what products like Purigen are supposed to do? And, if the likes of Purigen are effective, why do we not hear mention of this on UKAPS? Do you know of anyone that uses Purigen or similar materials?

Edit: I do realize that some organics, e.g. humic substances, are beneficial. So, perhaps the only solution to the surface film problem is the surface skimmer. Although I have an Eheim skim350, I have found it difficult to get it to work reliably and it's another unwelcome piece of kit in an 125l tank.

JPC

 

[jaypeecee]

Hi Folks,

I was reading Diana Walstad's book* today and she was discussing allelopathy. She says "Aquatic plants probably release large amounts of allelochemicals, for they are leaky when they're alive...". This supports what @dw1305 has previously mentioned. That made me think. Is this why we sometimes see BBA growing along the edges of leaves? Is it from here that plants are leaking nutrients/organic compounds into the water column?

* Ecology of the Planted Aquarium

JPC

 

[jaypeecee]

Hi Folks,

Although the question raised by my original post in this thread has been answered, may I return to the question that I put forward in post #70? My interest in organics continues and I wonder if it gets the attention that it possibly deserves? It was surface film on the water that prompted me to ask the original question. But, I now wonder what part organics play in promoting algae and cyanobacteria (aka BGA), just as one/two examples. In using the term 'organics', I mean all of the following:

DOC (Dissolved Organic Carbon)
DOM (Dissolved Organic Matter)
Particulate Organic Carbon
Organic Compounds
etc!

Referencing the same source as in post #71, it seems that many organic compounds released by aquatic plants decompose very slowly - we're talking weeks, months and longer. Frequent water changes are obviously one way of controlling organics. Another is the use of activated carbon or products such as Seachem's Purigen.

Any and all feedback would be appreciated.

JPC

 

[dw1305]

Hi all,

it seems that many organic compounds released by aquatic plants decompose very slowly

The rate of decomposition is directly related to the energy balance between energy expended in decomposition and the energy harvested. Carbon : nitrogen ratio is also important.

Sugars and proteins are easy to decompose, because they can be dismembered very easily. Lignin and humic compounds are slow to degrade because the energy expended in their decomposition is almost equal to the energy harvested. If the energy expended in decomposition exceeds the energy harvested then a substance isn't biodegradable.

That is why you can add potato starch to a plastic polymer, it tips the balance to "biodegradable".

cheers Darrel

 

[jaypeecee]

Hi @dw1305

Thanks for your reply.

So, my question is - how do we mitigate against organics building up? I realize that you're not in favour of testing water parameters but do you know how we can quantify and control organics building up? What about activated carbon and the likes of Purigen?

JPC

 

[Wookii]

Hi @dw1305

Thanks for your reply.

So, my question is - how do we mitigate against organics building up? I realize that you're not in favour of testing water parameters but do you know how we can quantify and control organics building up?

Dissolved organics are most easily removed by maintenance. Water changes are the most effective method to remove them, and why we do such large and regular water changes. Also cleaning the filter more regularly, not overfeeding fish, removing dying and loose leaves, siphoning any detritus build up etc will all help lower organics, but water changes are perhaps the most effective.

Dissolved oxygen levels also obviously help break down organics, so maximising DO should also help break down organics more effectively. Surface skimming is also effective as you have already mentioned - since it removes the organic film on the water surface, removing those organics, but also increasing gas exchange (and presumably DO levels) (PS - if you want a much more effective and easier to use skimmer than the Eheim 350, try the APS SKIM-2).

Darrel will I'm sure be able to give you more detail, but monitoring TDS is the simplest way to track gradually increasing organics - though if you use tap water for water changes, you need to keep an eye on tap water TDS also as mine varies quite a lot throughout the year.

What about activated carbon and the likes of Purigen?

JPC

Activated carbon is a bit more indiscriminate and will absorb a wider range of substances. Purigen is marketed as absorbing mainly dissolved organics. I use it in my filters, as I imagine do the majority of high tech tank owners on this forum, and it appears to be an effective addition as far as I am able to observe.

 

[dw1305]

Hi all,

So, my question is - how do we mitigate against organics building up? I realize that you're not in favour of testing water parameters but do you know how we can quantify and control organics building up?

I have measured TDS, in more polluted water, by "evaporation to dryness", it is much <"more difficult in cleaner water">, because you have to evaporate a very large volume of water to get a measurable amount of TDS.

Water changes are the most effective method to remove them, and why we do such large and regular water changes.

Pretty <"much exactly what"> @Wookii says, water changes and high DO are my default as well. It is back to the <"BOD concept">, as the organic load goes up you need to add more oxygen to process it, and more water changes (and plants) to dilute the remaining water.

<"Humic substances are persistent"> because they have a low BOD.

What about activated carbon and the likes of Purigen?

I like <"some tint in the water">, so charcoal or Purigen doesn't make any sense for me.

If I kept <"Lake Tanganyika fish"> I would want clear water, but for soft water fish I think some humic compounds offer an advantage. I don't measure the tint, I just adjust it by eye.

In my earliest incarnation as a fish-keeper <"I had a lot of water issues"> , some of which manifested themselves in tinted water, but water changes put a stop to that.

cheers Darrel

 

[jaypeecee]

Hi @Wookii

...monitoring TDS is the simplest way to track gradually increasing organics...

If you have the gear to actually measure total dissolved solids, then that would be a possibility. But, if you rely on a 'TDS' meter, you'll be in for a surprise. These meters measure electrical conductivity and convert this to a TDS reading. The problem is that many organic compounds will not register on a TDS meter as they are not electrically conductive. Try it for yourself. I just took 250ml of rain water (from a rain butt). Its conductivity was 93 microS/cm. I then added 1/8tsp (0.63ml) of granulated white sugar and stirred very well. The resulting conductivity was 93 microS/cm. Zero change. Try it for yourself sometime. Common salt, on the other hand, is comprised of sodium and chloride ions in solution and is detectable by a TDS meter.

JPC

 

[Wookii]

Hi @Wookii


If you have the gear to actually measure total dissolved solids, then that would be a possibility. But, if you rely on a 'TDS' meter, you'll be in for a surprise. These meters measure electrical conductivity and convert this to a TDS reading. The problem is that many organic compounds will not register on a TDS meter as they are not electrically conductive. Try it for yourself. I just took 250ml of rain water (from a rain butt). Its conductivity was 93 microS/cm. I then added 1/8tsp (0.63ml) of granulated white sugar and stirred very well. The resulting conductivity was 93 microS/cm. Zero change. Try it for yourself sometime. Common salt, for example, is comprised of sodium and chloride ions in solution and is detectable by a TDS meter.

JPC

You have to remember you're running a hobby aquarium not getting ready to draft a scientific white paper. Monitoring an aquarium, is about general relative values and a holistic overview, so seeing a gradual increase in TDS will give you an indication that you may have increasing organics. You're unlikely to get a pure increase in non-conductive organics in an aquarium, without an increase in conductive organics also, so you'll be able to measure any increase reliably enough to know if you need to increase water changes and maintenance to keep it stable and stop it rising continually. If your increased water change schedule halts the steady increase in TDS, then you now your intervention was the correct one.

 

[jaypeecee]

Hi @Wookii

I had hoped that we could discuss this in a friendly manner. But, I sense that it's not going that way. That's a real shame.

JPC

 

[Wookii]

Hi @Wookii

I had hoped that we could discuss this in a friendly manner. But, I sense that it's not going that way. That's a real shame.

JPC

Sorry if you misunderstood my post, nothing was intended as unfriendly in the slightest way?