Using deep gravel and bacteria to control nitrogen

[cwindram]

[quote]...my experience (and if you read this whole thread, you learned this) is that I'm a relatively bad plant keeper because my tanks mostly have high current and low low light. So for me, the model doesn't work as well.

I love your emergent plants in your tank. How are you supporting them in the tank? I presume there are poles (it looks like bamboo) holding the baskets in place, but am I seeing that right?

Thanks,
Eric[/quote]

Yes, Eric, there are bamboo crossbars, with plastic plant pots zip tied to them. I've tried various methods of supporting the plants, this seems to the best system I've come up with here yet. Most of the pots don't have any substrate, just a bare root plant, and the roots tend to grow through the drainage holes in the pots over time. A few of the plants have a bit of gravel or "fuller's earth" in the pot...which is like a clay gravel which provides some minerals to the plant. And some of the plants are grown in a "breeder box" which hangs over the side, which has circulation driven by an airline. Anyway, you can have plenty of water movement inside the tank with this method, and it doesn't disturb the plants. And because the plants are at the top of the tank, light levels can be kept low in the tank itself. (Couldn't figure out how to use the quote function correctly - maybe somebody could educate me on this).

[dw1305]

Hi all,

....... Maybe a bit off-topic, but I have always used plants to control nitrogen... all of my tanks have live plants, and there is never any measurable nitrate in them, in fact I sometimes add a general fertilizer to help grow the plants. I've got a recent setup (50 gals) going that's almost exclusively emergent plants, and this leaves lots of swimming space in the tank. ........

Not off topic for me. I tell people that planted systems (with "plant / microbe" biofiltration, there is no "plant only" biofiltration), particularly like yours where plants have access to atmospheric CO2 and oxygen, are an order of magnitude more effective than "microbe only" systems, but they don't all believe me.

For whatever reason some aquarists are resistant to the idea that plants can be an important component of biological filtration, but it is the honest truth.

...... my experience (and if you read this whole thread, you learned this) is that I'm a relatively bad plant keeper because my tanks mostly have high current and low low light. So for me, the model doesn't work as well.

@beekateen I understand that, and high current does, to some degree, mitigate against low dissolved oxygen levels. High levels of dissolved oxygen are the key metric, it doesn't really matter how you get there, I just like a system without (m)any "single points of failure" in the way that @aquaholic outlines for their drip system.

..... but my city council water often has high levels of ammonia, partly because of chloramine dose fluctuations and partly because of cleaning activities. There is no prior warning, no indication how long this lasts and with several fish rooms, having to delay a scheduled water change day creates problems.

I solved this issue very easily with a slow constant drip (automatic) water change that displaces old water out. No timers, valves, mechanical devices. There are multiple other benefits to constant drip but this solved the poor water quality issue instantly and removes nitrate build up issue at the same time.

I run a few hundred tanks on central filtration systems, all bare bottom but do keep several 55 gallon drums full of gravel to keep biofilm - aquatic stability. They have not been disturbed for almost 15 years.

Could you add a floating plant to the drums? I know you are limited with what you can grow in Australia. I think that, dependent on which state you live in, that Nile Cabbage / Water Lettuce (Pistia stratiotes) might be an option?

cheers Darrel

[aquaholic]

I deliberately keep light levels low in my fish rooms to reduce tank maintenance however to provide the vivid pop of intense natural colours that all wild caught fish have, I culture 3 x 2000L tubs of green water algae on a weekly rotation which is flood fed (opening a valve) through my tanks - adult brood stock and growout stages all benefit. Additionally I have a 6m long bed of scoria containing edible pandan plants. The water table level rises and falls within the scoria via a siphon (no moving parts) so essentially a wet - dry filter. Plants get fed to the fish. I'm constantly asked for submersed pandan for peoples ponds so some gets sold when I need to remove excess.

I also have anoxic baskets on one system and anoxic like baskets with plants on another. Both seem to work but it's very hard to beat automatic (constant drip) water changes as essentially there is nothing to do. Very small drainage hoses can be used to remove slow drips to waste for anyone wondering how to provide drains.

[dw1305]

Hi all,

...... I culture 3 x 2000L tubs of green water algae on a weekly rotation which is flood fed (opening a valve) through my tanks - adult brood stock and growout stages all benefit. Additionally I have a 6m long bed of scoria containing edible pandan plants. The water table level rises and falls within the scoria via a siphon (no moving parts) so essentially a wet - dry filter. Plants get fed to the fish. I'm constantly asked for submersed pandan for peoples ponds so some gets sold when I need to remove excess.........

Perfect system.

You might be interested in: Bartelme RP, Oyserman BO, Blom JE, Sepulveda-Villet OJ, Newton RJ. (2018) "Stripping Away the Soil: Plant Growth Promoting Microbiology Opportunities in Aquaponics." Front Microbiol. 22;9:8.

cheers Darrel

[aquaholic]

Hello Darrel,
Thank you for the article suggestion. Interesting but inconclusive reading creating unsatisfactory learnings.

I think we already know the importance of microbial activities especially in plant root zones. Similar to moving bed bio reactors - biofilm filters (bacterial colony diversification) providing superior biological filtration over traditional nitrification bacteria there is so much we don't know or understand yet we don't need to fully understand to obtain benefits. I changed from wet - dry filtration to MBBR after running both side by side in comparison tests for several years. The wet - dry filters were adequate but MBBR were better (for me) as multiple filtration passes are provided per single water pass. Despite me trawling through many scientific articles on biofilm research for many years, it was enough to simply acknowledge we can still benefit without knowing exactly how or why.

The struggle over fish - plants - soil outlined was easy for me. I prioritise fish over plants so all the plants are expendable and plant density - diseases are never an issue. Plants provide spawning material, refuge, fish and human food, as well as improved water quality. While I'm sure fractional improvements are possible, expanding an imperfect system is practical and easy way to boost performance.

[dw1305]

Hi all,

Thank you for the article suggestion. Interesting but inconclusive reading creating unsatisfactory learnings.

I think you are right, we are still very much in a "shades of grey" world. Personally I think we are at the beginning of the discovery of novel ammonia oxidising microbes (AOM), and that the next ten years will be as least as revelatory as the last ten.

I think we already know the importance of microbial activities especially in plant root zones.

I wish, I do, but I think that generally aquarists are still a long way behind where the science is. Personally I'm very sceptical, a bit of a luddite, a great believer in KISS & "if it ain't broke don't fix it" solutions, but I think you have to embrace solid science. I'm old enough to remember when yellow tinted, aged water was regarded as an elixir of life, rather than an inevitably toxic brew, and plants as purely decorations* and irrelevant to biological filtration. Judging from a lot of more email correspondence we still have a remarkably large number of people who haven't fully bought in to the importance of plants*, the rhizosphere, AOA, COMAMMOX Nitrospira etc.

Similar to moving bed bio reactors - biofilm filters (bacterial colony diversification) providing superior biological filtration over traditional nitrification bacteria there is so much we don't know or understand yet we don't need to fully understand to obtain benefits. I changed from wet - dry filtration to MBBR after running both side by side in comparison tests for several years. The wet - dry filters were adequate but MBBR were better (for me) as multiple filtration passes are provided per single water pass. Despite me trawling through many scientific articles on biofilm research for many years, it was enough to simply acknowledge we can still benefit without knowing exactly how or why.

Moving Bed Bioreactors (MMBR) definitely give you most bang for your buck. This is from "Elliott, O., et al. (2017) "Design and Manufacturing of High Surface Area 3D‐Printed Media for Moving Bed Bioreactors for Wastewater Treatment." Journal of Contemporary Water Research & Education 160 pp. 144-156."

........ The specific surface area and topology of a biofilter media carrier is one of the most important parameters that determines the performance and efficiency of the system. In this work, mathematical models and 3D printing technologies were used to design and fabricate complex media designs that provide high specific surface area and refugia to protect biofilm from premature sloughing. Several gyroid based designs were proposed with specific surface area well beyond 2300 m2/m3. However, wall thicknesses and pore sizes that are prone to clogging determined a design that yields 1168 m2/m3 (133% larger than the baseline commercial K1 Kaldnes). Several moving bed bioreactors were constructed for laboratory testing with inoculation provided by wastewater from a fisheries operation. Preliminary results indicate that the 3D printed media can withstand the prevalent conditions in moving bed bioreactors, and that the NH3 removal rate of gyroid media is comparable to that of K1 Kaldnes........

The struggle over fish - plants - soil outlined was easy for me. I prioritise fish over plants so all the plants are expendable and plant density - diseases are never an issue. Plants provide spawning material, refuge, fish and human food, as well as improved water quality. While I'm sure fractional improvements are possible, expanding an imperfect system is practical and easy way to boost performance.

I was originally interested in plants purely as aids to water quality, but I now realise that I had severely underestimated the synergistic effect in plant /microbe biological filtration.

cheers Darrel

[dw1305]

Hi all,

TY for posting this Darrel.

Years ago I used to read the bacteria came into tanks from the air. I did not accept this as the normal route. I worked in Saudi Arabia int the late 1970s. I was there when it was 130F in the shade and you could not see your sweat because it evaporated as fast as you made it. There is no way floating bacteria were surviving in that dry air.

I'll guess that atmospheric transfer isn't that important, but I can also see that it will happen in most circumstances, purely because the fauna and flora of ephemeral water bodies is incredibly proficient at finding new "puddles".

Because of that I'm also going to guess that organisms (like AOA, AOB, Nitrospira etc), which are orders of magnitude smaller and more numerous, are always going to find your tank sooner or later.

I can see why my tanks might be slightly different to the norm, and why that might mean they get an appropriate starting inoculum of microbes and become "cycled" without any direct intervention* on my part.

*I use rainwater, I always have running tanks and from these I transfer plants, substrate, filter mulm, and these are all going to be inoculum sources, supplying an appropriate oligotrophic assemblage of archaea and bacteria .

cheers Darrel

[Procrypsis]

+2 on the RO system.
I run mine and capture the "waste water" to flush toilets, laundry, etc. Nothing goes to waste.

[dw1305]

Hi all,
To revive a "zombie" thread .......

<"At UKAPS"> we've recently talked with the scientists from the <"Neufeld lab."> at the <"University of Waterloo">.

One aspect that their research group is working on are the microbes found in freshwater aquarium filters and how aquarium conditions might affect that assemblage. Dr Neufeld is a long term aquarist <"pp. 14 - 20- Strangers in your home: Archaea thrive in aquarium biofilters">

I can't thank Josh (and Michelle McKnight) enough for their time, and if people are interested in the actual process of nitrification, their scientific papers (and the UKAPS thread) are well worth a read.

cheers Darrel

[Jools]

Think of it as reviving Elvis, or Ghandi, or whatever works for you. Not dead, just resting....

Thanks for the update, I've always "felt" there was something in this.

Cheers,

Jools

[dw1305]

Hi all,

Thanks for the update, I've always "felt" there was something in this

It is still a really interesting area.

Reading between the lines, I think they feel that ammonia (NH3) and nitrite (NO2-) are an answered question, but they are particularly interested in a microbial "answer" to nitrate (NO3-) accumulation.

I can see the commercial imperative for this and I note that they have a research project with Hagen.

Personally I'm less bothered about NO3- accumulation, I am pretty confident that plants are the answer (although I always think that plants are the answer, whatever the question is).

Cheers Darrel