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The construction of the optimal nitrification filter

Lasse

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In many threads – the nitrification process is discussed. This thread will try to handle how to construct the optimal nitrification filter for an aquarium. I´m aware that all does not have possibility to do an exactly copy of this, but the principles are general principles. It is important that this is a try to outline a filter that not exist in my aquarium – I have not try it – but I have tried to sum up my 50 years of experiences with this process. From aquariums, from wastewater treatments plants and from fish farms

Examination the nitrification process.

It is a 2-step process
  1. In the first step NH3/NH4 (ammonia gas or ammoniac/ammonia ion or ammonium) is oxidized (converted with help of oxygen) into nitrite by many types of autotrophic bacteria (AOB = Ammonia Oxidizing Bacteria) and archaea (AOA = Ammonia Oxidizing Archaea)
  2. In the second step NO2 (nitrite) is oxidized into NO3 (Nitrate) by a few autotrophic bacteria genera including Nitrobacter and Nitrospira (NOB = Nitrite Oxidizing Bacteria)
Both steps are done by organisms that are classed Autotrophic organisms. This means that the do not take their energy by consuming organic matter – they take their energy from other sources. The most well-known Autotrophic organisms is those that use photosynthesis. It means – they use visible light as an energy source – plants, algae and some bacteria. However, the organisms responsible for the nitrification cycle does not use light as energy source – instead they use chemical stored energy – they are often referred to Chemoautotrophs. The first step they use the energy differences between stored energy in NH3/NH4 and NO2 – the second step use the same difference between NO2 and NO3.

Needs of the nitrification process

Both steps need surface to attach on

Both steps are very oxygen dependent. In fresh water there is studies showing that the first step can work at oxygen content of 3 mg/L O2, but the second step need at least 5 mg/L O2. Worth to mention here – saltwater content around 1.5 mg/L lesser O2 in the same temperature as freshwater – which means that saltwater at 25 degree C contain around 6.8 mg/L O2 at 100% saturation. Knowing of experiences that a reef aquarium with a good skimmer but no reversed refugium often run around 80 % saturation in nights (around 5.5 mg/L O2) is rather clear that the environment in our aquariums many times are a disadvantage for the nitrification cycle. If the second step stop or not work in the same rate as the first step – NO2 will be built up – something that often happens in newly started aquariums – often referred as “halted” nitrification. Please see this thread

Both steps (or more accurate the microorganism involved in the steps) need inorganic nutrients. N is no problem, but P can be a problem in newly started aquaria and has been reported as major cause for a stalling process – when adding PO4 – the second step started directly.

Both steps take inorganic carbon in form of CO3 (or HCO3) – they are alkalinity consumers. In freshwater – it can be a problem in water with low alkalinity (with following low pH – Low alkalinity water with pH below 7 stops the process – however is not the pH – it is the lack of CO3/HCO3 that stop the growth). In systems with adding CO2 for plant growth is normally recommended to use HCO3 in order to rise and retain the alkalinity around 2 in KH before starting the addition of CO2 in order to get a stable aquarium with working nitrification. In saltwater – no problems – the natural alkalinity is more than enough

For both steps - The organisms are slow growers compared to heterotrophic bacteria. Doubling time over 13 h compared with 15 to 30 minutes for heterotrophs

For both steps - After first establishment – they can go dormant for a while if the environment get hostile for them (an invasion of heterotrophs as an example). When the environment is good again, they come back rather fast in full strength

Summary – optimal conditions for nitrifiers
  1. Enough space to colonize and maintain colonized and in direct contact with the streaming water
  2. No or few heterotrophs that compete about space
  3. Good oxygen concentration in the interface between biofilm and water
  4. NH3/NH4 (first step) and NO2 as energy resource
  5. Some PO4 in the water
  6. Alkalinity above 2 in KH
The filter should give
  1. A possibility for a fast flow that polishing the filter material
  2. The filter material should be course enough that it allows a thin interface between water and material all over the filter. Small pores should be avoided
  3. Free access for air in the whole filter
  4. Possibility to have a reversed flow of air through the filter – from the bottom up through the top
  5. Even spread of the water through the filter
  6. As high and maybe as narrow as possible allowing a strong stream through it
  7. No solid bottom - the water should not accumulate in the filter. Bottom of plastic grid as an example
  8. The water – flushed biofilms comes out into the water: If placed in sump – place it before the skimmer if you want the skimmer to take away the bacteria – if you want it up to your corals – place it before the return pump.
Proposed construction

nitrification-filter.jpg

Advantages of this type of filter
  1. High rate of nitrification over time
  2. Because the filter material will not be in water if the pump stop – no risk of forming of hydrogen sulphide gas
  3. No cleaning or back flushes needed
  4. High gas exchange allowing ammonia gas (ammoniac) be aerated out. Oxygenate the water if the O2 level is below saturation and take out O2 if the water is supersaturated. CO2 – see below
  5. If the air has low content of CO2 (outside air or air scrubbed by a CO2 scrubber) it will rise the pH if it is low in the water (below 8.15 for outside air) and if the pH is above 8.15 (outside air) it will lower the pH (adding more CO2 to the system)
Disadvantages with this type of filters (and all aeration like skimmers)
  1. If any there is any volatile gases in the room – it will transport them into the water up to the equilibrium point for this gas and water.
  2. If the room have high content of CO2 – it will lower the pH – ventilation with outside air may help
  3. Need space and height
  4. May remove all NH3/NH4 too quick and it could harm some organisms that use photosynthesis (the ones that can´t handle NO3 as a source for inorganic nitrogen)
  5. It will be a faster evaporation of water and require more top off (Thank you @Miller535 for that input)
Advantages/Disadvantages

  1. the tower will act as an heat exchanger - it can be both a advantage/disadvantage depended of temperature difference between the aquarium and the air used in the tower.

Possible remedies for some of the disadvantages
  1. Because the filter material will not be in water if the pump stop – it is possible to let the pH manage the filter and also only use it during 2-4 hours after feeding when the load of free NH3/NH4 is largest


Sincerely Lasse
 
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Aquarium Specialty - dry goods & marine livestock

brandon429

why did you put a reef in that
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since no reef tank is lacking surface area with just its live rocks, can carry the same fish bioloading that live rocks, sand, and that filter will carry, when would a reef tank need the extra nitrification help?

agreed that design is perfect and efficient and will convert ammonia powerfully. i like your mention of surface area we don't study that much in the hobby.


live rock is already filtering though, to the point extra filtration won't make a measurable help/change/difference in a reef tank but it would in fish production facilities, fish-only setups it seems
 
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jda

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Lets please don't deal in absolutes and hyperbole. There are certainly are plenty of reef tanks where surface area is not enough and filters are needed. With enough experience and getting out to see other setups, these are easy to find. Can we at least agree to be responsible adults and say things like "some" or "most" tanks, or just leave it out all together.

Lets also not forget that most modern tanks are not set up with live rock, but with calcium carbonate or dolomite shaped decorations that are so full of terrestrial organics that they will not be suitable to function as an effective bio filter for a few years in some cases.

Thank you Lasse for writing this up. Nearly everybody should read this unless to at least understand and for some with newer tanks set up with sterile material to possibly implement.
 
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MabuyaQ

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since no reef tank is lacking surface area with just its live rocks, can carry the same fish bioloading that live rocks, sand, and that filter will carry, when would a reef tank need the extra nitrification help?

agreed that design is perfect and efficient and will convert ammonia powerfully. i like your mention of surface area we don't study that much in the hobby.


live rock is already filtering though, to the point extra filtration won't make a measurable help/change/difference in a reef tank but it would in fish production facilities, fish-only setups it seems
The future of reefing will be using less and less live rock because it isn't sustainable. 3D printed calciumcarbonate structures for mounting corals will replace all kinds of rocks. These kind of filters will than take care of the biological filtration, add a batch-process denitrification filter and you can even go skimmerless.
 

EMeyer

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The future of reefing will be using less and less live rock because it isn't sustainable. 3D printed calciumcarbonate structures for mounting corals will replace all kinds of rocks. These kind of filters will than take care of the biological filtration, add a batch-process denitrification filter and you can even go skimmerless.
It is simply not true that live rock is not sustainable. Just because it has sometimes been collected in unsustainable ways, does not make it categorically unsustainable. Better to say "some live rock is collected in unsustainable ways".

Trees take decades to mature but we harvest them in sustainable ways. Live rock can be cultivated in a couple of years, making it much easier than trees. There is no shortage of suitable rock in or near the ocean (it is widely used as landscaping fill for construction projects in tropical regions), and no shortage of space in which to cultivate it into live rock.

I'm afraid the shortage of live rock is caused by inappropriate regulations rather than any inherent sustainability of the material. But reef keepers do not have enough clout to influence politics, sadly. We are just too small a group.
 

brandon429

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one good thing about real live rock from from the 90's- 2000's is it lasts forever (as long as we keep it in a controlled environ)

that w drive up the price like gold nuggets one day, permanent biodiversity pumps- true coralline aquarium cured ocean originated live rock. dense heavy lr

I wouldnt sell my nine pounds of real live from from the 2000's for any reasonable amount it will be part of my permanent hobby experience. it never stops producing and housing worms and pods each decade if kept fed/clean. I believe it will never stop as long as the system runs (feed in, waste out) true unlimited biological lifespan animal producing rock.
 
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Lasse

Lasse

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Isn't this like one of those wet dry filters?
The real name is trickle filter and its not my invention. I know that there is people naming this a wet dry filter bot that´s in reality is a total different filter build on batches. You fill water in a filter, wait for some minute and empties it completely a so the air comes in contact with the filter media. It is a very good filter too but has the disadvantages that it is with time will be filled of organic matter and not longer works as an nitrification filter.

Just need a good prefilter so organic matter don't build up.
The secret with this filter is that you do not need any pre filter because the water should have enough of speed in order to polish the filter media. IME - if you look at the picture below the number forth from the left is the best to use in this type of filters of these 5 - But that type (number 4) with 6 apartments and the double diameter is best. Is not only a question of area is also a question that it is only the area that will be polished that give the best nitrifikation rate when used in a static bed. We did experiment with moving beds and nitrification rate using both K1 media and the new K5 media. The K5 media was much better in nitrification rate compared with the K1 media. But in a fixed bed - I prefer to use more simple media with lesser apartments. A media of K5:s size but only 6 apartments would be perfect IMO.

1600273697033.png

Sincerely Lasse
 

jda

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This filter uses a pump instead of gravity. This pressure is what helps to wash the media. It also is presumably after a mechanical filter of some sort.

This is similar to how bio balls and other plastic media does not accumulate particles and detritus in a downdraft or beckett skimmer.
 
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Lasse

Lasse

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This is similar to how bio balls and other plastic media does not accumulate particles and detritus in a downdraft or beckett skimmer.
Yes it is the same principles and a downdraft skimmer is nothing else but a nitrification tower and aerator :D

Sincerely Lasse
 

ReefGeezer

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We built "ammonia towers" in the 90's that functioned in the same manner. 8' lengths of 6" PVC, filled with bioballs and fed by a high volume/high pressure pump. They were super efficient. Ammonia & nitrite were always 0 even in super heavily stocked systems but nitrates were always high. These filters aren't intended to address nitrate reduction. We didn't care back then. They were used in fish only holding systems.
 

MabuyaQ

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It is simply not true that live rock is not sustainable. Just because it has sometimes been collected in unsustainable ways, does not make it categorically unsustainable. Better to say "some live rock is collected in unsustainable ways".

Trees take decades to mature but we harvest them in sustainable ways. Live rock can be cultivated in a couple of years, making it much easier than trees. There is no shortage of suitable rock in or near the ocean (it is widely used as landscaping fill for construction projects in tropical regions), and no shortage of space in which to cultivate it into live rock.

I'm afraid the shortage of live rock is caused by inappropriate regulations rather than any inherent sustainability of the material. But reef keepers do not have enough clout to influence politics, sadly. We are just too small a group.
Flying that rock live or dead around the world to put in a tank is not sustainable. Never was and never will be. Technology and knowledge has progressed to the point that it isn't even necessary anymore, if we wanted/choose to.
 

Larry L

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Nice writeup @Lasse , thank you!

Because the filter material will not be in water if the pump stop – no risk of forming of hydrogen sulphide gas
I think this is a big advantage compared to a lot of nitrification systems.

Because the filter material will not be in water if the pump stop – it is possible to let the pH manage the filter and also only use it during 2-4 hours after feeding when the load of free NH3/NH4 is largest
Is there a concern about the bacteria cultures staying alive if the filter dries out too much?

Also, I assume you would you want to use an opaque filter to keep light out, correct? Even if just to reduce algae growth on the biomedia?
 

Sisterlimonpot

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Lasse,
English is the only language I speak, so I have admiration for you writing this in English. I'm trying to wrap my mind around what it is that you're suggesting. Are you saying that you flow water through a tube with 6 chambers for maximum surface area, minimizing flow restriction to achieve nitrification process?

I took your examples and applied what I thought you were trying to convey and sketched this up in solidworks. Are you suggesting something like this:


If so, is the goal to have one tube or multiple tubes for water to flow?? How much surface area is needed for a standard bioload? And it appears that you are taking advantage of it being exposed to air for off gassing, and suggest that it may only be needed to run a few hours after feeding, what happens to the bacteria that was cultivated on the surface when water is no longer passing over it? Does it die off?

Hopefully, I get the gist of what you're suggesting and I look forward for your clarification.
 
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Lasse

Lasse

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Lasse,
English is the only language I speak, so I have admiration for you writing this in English. I'm trying to wrap my mind around what it is that you're suggesting. Are you saying that you flow water through a tube with 6 chambers for maximum surface area, minimizing flow restriction to achieve nitrification process?

I took your examples and applied what I thought you were trying to convey and sketched this up in solidworks. Are you suggesting something like this:


If so, is the goal to have one tube or multiple tubes for water to flow?? How much surface area is needed for a standard bioload? And it appears that you are taking advantage of it being exposed to air for off gassing, and suggest that it may only be needed to run a few hours after feeding, what happens to the bacteria that was cultivated on the surface when water is no longer passing over it? Does it die off?

Hopefully, I get the gist of what you're suggesting and I look forward for your clarification.
No not directly - I suggest very thin wheels with 6 spokes - maybe 1-2 mm thick. But your idea is not so bad either but you need many, many spokes - not 6. Because air should have contact with the thin water film all over the construction it could be difficult to have an even distribution of the water from the top with a tube like yours but with + 100 spokes. In wastewater treatment - there is already a material that is close to your suggestion

1600330327798.png

In a fish farm I worked at in the 80:ties we had 6 m high towers with this material. The bricks was around (if I remember right) 1 * 0,5*0.5 m and was stacked as lego blocks to a filter 6 * 4 * 2 m. We run 200 cubic metres/ hour over these tower 7/24. These was effective - in one line (every line had only i tower) we could feed with around 170 kg/day dry pellets without nitrite build up to a higher concentration than 0.2 - 0.4 as a peak in late evenings. In the morning, with 12 hours without feed - NO2 levels was 0. We start to feed again and around 21:00 (we stop feeding at 20:00) it was around 0.3 mg/L again. The plant was in operation for 4 years and during that time - no clogging happens.

Is there a concern about the bacteria cultures staying alive if the filter dries out too much?
IME these bacteria and archaea - when they once are established - can go dormant and can stay dormant for a long period if there is no water. But let us say that half the population has "died of" during a week without water (or most important - without any energy input) - it will only take a day before it is up in the population that respond to your feeding regime. In the example with the fish farm - we could be stop the feeding for 24 - 48 hours and start it again with the same feed regime - if it was a longer stop - we rise the feed stepwise during 2 - 3 days. And it was european eel we farm. pH was 7 and was withhold with limewater. Adding limewater in a freshwater system will rise the Ca content during time. NaHCO3 is a better choice IMO - and in the last indoor fish farm I worked at we use that in order to withhold an alkalinity around 3 in KH. In the 80:ties it was not very well known that it was alkalinity - not pH - that was the critical factor.

Would there be any benefit to injecting air into the bottom portion of the filter like is often found in out trickle filters/towers?
Yes but there is an easier and more effective way. The bottom is free from water and open to the air. Make a cap over the top and place a fan that suck air from the bottom to the top and out in the air. It is very effective

I would inject medical grade oxygen. If I done start a fire.
Have already test that :p The cost/benefit factor was not great enough to make the method usable - biological very good but......

But I have other ideas - including internal produced oxygen - in another type of filter........

We built "ammonia towers" in the 90's that functioned in the same manner. 8' lengths of 6" PVC, filled with bioballs and fed by a high volume/high pressure pump. They were super efficient. Ammonia & nitrite were always 0 even in super heavily stocked systems but nitrates were always high. These filters aren't intended to address nitrate reduction. We didn't care back then. They were used in fish only holding systems.
Yes - it is not mine construction or idea as I state in the beginning. IMO - if you should have a very effective nitrification and denitrification the same time (or nearly in the same time) you need to optimize each process and you need to do it in separate processes because their demands are opposite on two important points.
  1. Nitrification -> need high oxygen environment; Classic denitrification -> need no oxygen environment
  2. Nitrification -> no DOC in the water; Classic denitrification -> need DOC in the water
I do not believe in system that should manage both tasks the same time - at least not these that rely on classic biological principles if you should optimize both processes.

However - in a normal loaded aquarium maybe solution as BADES (see Belgian Anthias threads and posts) may work - I do not know because I have not test it. But I prefer to have a fast and effective nitrification process. The goal with this thread was partly to explain the process - parly show a filter that is optimal constructed after these demands

My wish to have a good working nitrification process may get some support from @AquaBiomics result. In some place I saw that he report a surprising high concentration of nitrification organisms genome in water from very successful reef tanks. Correct me if I´m wrong

Sincerely Lasse
 

MabuyaQ

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Lasse,
English is the only language I speak, so I have admiration for you writing this in English. I'm trying to wrap my mind around what it is that you're suggesting. Are you saying that you flow water through a tube with 6 chambers for maximum surface area, minimizing flow restriction to achieve nitrification process?

I took your examples and applied what I thought you were trying to convey and sketched this up in solidworks. Are you suggesting something like this:


If so, is the goal to have one tube or multiple tubes for water to flow?? How much surface area is needed for a standard bioload? And it appears that you are taking advantage of it being exposed to air for off gassing, and suggest that it may only be needed to run a few hours after feeding, what happens to the bacteria that was cultivated on the surface when water is no longer passing over it? Does it die off?

Hopefully, I get the gist of what you're suggesting and I look forward for your clarification.
You should 'stack' them side by side. A honeycomb with internal substructure is also frequently used, or just rows of triangles.
 
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