# Can a canister filter 'stall'



## alan'67 (10 Jul 2017)

Reading an earlier thread posted by Darrel about a chap and his blog ( good read by the way) kind of set my mind to thinking about ammonia absorption by plants in the tank and the effect on a canister filter. 

I'm beginning to wonder if my 18 month old canister filter is still working biologically as it were.

To add a bit more detail, I'm currently running a Rio 180 tank with the internal filter still installed, with 70% of the sponges fitted and in addition a JBL 1501e underneath in the cabinet.

Plants are mostly crypts a few hygrophila and swords planted in a soil substrate and the critters are 12 tetras and half a dozen corydoras catfish.

The reason I'm beginning to suspect a problem is that when I clean the filter sponges there is next to no build up of mulm/detritus of any kind on any of the sponges at all. Sure there is some dirt in the bottom of the case as well as around the impellor but not much else considering the general poor state of the plants!. 

Compare to my partners 306 canister on her 100 litre planted tank and after 6 weeks you could plant potatoes in all the crud that washes out of that filter. The difference between the two filters is chalk and cheese.

The same could be said about the health of the plants to tell you the truth!.

Plus I'm still getting diatoms! .............after 18 months!!. 

I do approx. 80% water changes per week and I wonder what with this and my small fish load, what little ammonia there is, will be absorbed by the plants long before the bacteria in the filter gets it's chance.

Does this sound reasonable or am I over thinking it somewhat?.


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## SA Aquatic (11 Jul 2017)

Can you upload some pics of the tank? Usually the plants and growth will give some indications


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## mort (11 Jul 2017)

Do you dose anything for the plants? I have a similar volume with a similar bioload and my filter is always surprisingly clean, but the plants thrive because I partially EI dose. It could just be that with such a low bioload, your plants are starving and the fish population is to low to cause much muck.


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## dw1305 (11 Jul 2017)

Hi all, 





alan'67 said:


> I'm beginning to wonder if my 18 month old canister filter is still working biologically as it were.





alan'67 said:


> To add a bit more detail, I'm currently running a Rio 180 tank with the internal filter still installed, with 70% of the sponges fitted and in addition a JBL 1501e underneath in the cabinet.





alan'67 said:


> The reason I'm beginning to suspect a problem is that when I clean the filter sponges there is next to no build up of mulm/detritus of any kind on any of the sponges at all. Sure there is some dirt in the bottom of the case as well as around the impellor but not much else





alan'67 said:


> Compare to my partners 306 canister on her 100 litre planted tank and after 6 weeks you could plant potatoes in all the crud that washes out of that filter. The difference between the two filters is chalk and cheese.


You are absolutely fine, the cycled/not cycled/stalled concept isn't really very useful. What you have is a continuum of the ability to process bio-load, dependent upon how efficient your bio-filtration is.

You can end up not getting much build up of bio-film by a number of routes. If you have a tank with snails and _Asellus (_detrivores_) _they will reduce a lot of the bio-film by grazing the surfaces, including inside the filter. This can be an issue <"in sewage treatment">, but not in a planted system. ]





alan'67 said:


> I do approx. 80% water changes per week and I wonder what with this and my small fish load, what little ammonia there is, will be absorbed by the plants long before the bacteria in the filter gets it's chance.


In your case (Rio 180) you have a planted tank with a lot of filtration and a relatively low bio-load. If you have a system where you have plenty of dissolved oxygen it will also reduce the bio-film, because it will be continually grazed by rotifers etc.

The little black bits you get left in the filter are the structural carbohydrates, that are very difficult to microbially bio-degrade. This just means that the energy produced by decomposition is almost equal to the energy expended in breaking them down, this is because all the _low hanging fruit_, the oxidisable material, the fixed nitrogen and sugars etc., have already gone.

I would look upon your situation as both normal and healthy, it just shows that the plant/microbe bio-filtration in the system (tank substrate, filter, plant surfaces) is running efficiently. If you increased the bio-load (or reduced the availability of oxygen) you would eventually begin to get more biofilm. 

In the case of your partner you have a situation where the filter is receiving less oxygen, and the water is probably becoming de-oxygenated within the filter, allowing the biofilm to develop (the schematic below is from a trickle filter, but similar zonation will occur).






This isn't necessarily a bad thing (this is how canister filters work in non-planted tanks), but the problem is that a finite amount of oxygen enters a canister filter, and you run the very real risk of the filter media becoming anaerobic, with disastrous results. 

cheers Darrel


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## alan'67 (11 Jul 2017)

Thanks for the replies guys.

I do dose ferts mort, at first it was EI and then an all in one made to James's recipe.

This was mainly to make things as simple as possible because I need someone else to look after things during the week.

Thanks for coming up trumps again Darrel with the explanation, it has put my mind at rest.

It sounds if there's at least one thing about my set up that's got the edge over the other half!.

It sounds as if her filter is close to the edge if she (me actually!)  doesn't keep on top of the cleaning regime?.

The more time you spend in this hobby, the more you realise just how important a role microbes/bacteria play in a healthy tank setup.

I'm going to try and post a few pictures (there not to good) to give you an idea of the tank at the moment.


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## dw1305 (11 Jul 2017)

Hi all,





alan'67 said:


> It sounds as if her filter is close to the edge if she (me actually!) doesn't keep on top of the cleaning regime?.


That is the one. If the filter stops functioning it isn't always disastrous in a planted tank, because as well as the ammonia uptake by the plants, the top layer of the substrate, and the zone around plant roots will still support microbial nitrification. 

If the filter sits a long way below the tank? you may find that water is dwelling in it for longer than you would like, or it maybe the filter media itself. 

I have an easy clean pre-filter on the filter intake and I don't like any mechanical filtration media inside the filter, so no floss or fine sponge, just alfagrog or sintered glass etc. 

cheers Darrel


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## alan'67 (11 Jul 2017)

Hi Darrel,

The filter does sit a fair way lower than the tank to be honest.

I guess having a pre filter on the intake takes can of large debris leaving the filter media for biological function?.

Would you need to put sintered glass/ alfagrog in a bag or leave it loose in the baskets?.

Also would you need to leave some sponges behind to seed the new media?.

Do you also know to what extent the microbes in the substrate and plant roots actually contribute to the nitrification process compared to the canister itself?.


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## dw1305 (12 Jul 2017)

Hi all, 





alan'67 said:


> The filter does sit a fair way lower than the tank to be honest.


This reduces flow. 





alan'67 said:


> I guess having a pre filter on the intake takes can of large debris leaving the filter media for biological function?


Yes, I just want the ammonia and dissolved gases in the filter, I don't want to use the filter as a syphon. The other advantage is that you can clean the pre-filter really quickly, without having to open the canister.


alan'67 said:


> Would you need to put sintered glass/ alfagrog in a bag or leave it loose in the baskets?. Also would you need to leave some sponges behind to seed the new media?.


I'd leave it loose in the basket, but it doesn't really matter and yes, leave in a sponge.

I like sponge as a filter media, just not anything finer than PPI20 grade. 





alan'67 said:


> Do you also know to what extent the microbes in the substrate and plant roots actually contribute to the nitrification process compared to the canister itself?.


 I'm not aware of any published work that actually quantifies it for aquariums (and every aquarium is different), but there is quite a bit of work on constructed wetlands, and that shows that plants make a huge difference to the efficiency of biofiltration.

This is from: Toyama _et al._ (2016) <"Effects of planting _Phragmites...."> Environmental technology", _*37*(4), pp.478-485.


> We examined the effect of planting an emergent aquatic plant (_Phragmites australis_) on nitrogen removal from sediments using a 42-d pot experiment. The experimental pot systems comprised two types of sediments planted with and without young _P. australis_. Total nitrogen (total N), total dissolved N, and NH4–N in the sediments decreased markedly after planting. In contrast, those levels decreased only slightly in the unplanted sediments. The decrease in total N in the _P. australis-_planted sediments was 7–20 times those in the unplanted sediments. Abundances of bacterial 16S rRNA, archaeal 16S rRNA, ammonia-oxidizing bacterial ammonia monooxygenase (_amoA_), ammonia-oxidizing archaeal _amoA_, and denitrifying bacterial nitrite reductase (_nirK_) genes increased significantly in sediments after planting. _Phragmites australis_ appears to have released oxygen and created a repeating cycle of oxidizing and reducing conditions in the sediments. These conditions should promote mineralization of organic N, nitrification, and denitrification in the sediments.


cheers Darrel


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## Silviu Man (12 Jul 2017)

Hi,

The most important process that take place in the filter, as well as in the substrate (but not at the same level) is the action of bacteria against ammonia and, consecutively, against nitritis that lead to nitrates. If we could have a second filter with anaerobic condition then nitrates could be denaturated and free nitrogen released. Unfortunately, this mean a huge volume and a very low flow rate of the water, that make it available only at the experimental level. Having in mind this, an external filter should be used first of all for biological filtration. This means a strong cleansing bacteria colonisation. This because why, most of the filters, for an efficient work,  are equiped with biological filter medium, with a large surface for bacteria fixation. This medium should not be filled with  organic particles, exactly because this will limit the flow of the water through that spaces. It work only for the chemistry of the water. For mechanical filtration are used pre-filters (internal or external) that, as it was writen here, can be very easy clean, change, anytime in anykind of water. This significantly reduce the amount of organic particles that flow in the filter and the proces of warping of the filter medium.

This work different for each tank. A well planted tank and/or with small number of fish, where is not much organic substances to be decomposed, doesn't need a very large biological filtration. Plant also make there a good job, as is writen in the above abstract, being the most important recommendation for cycling the aqvarium with plants inside. But, if in the tank are many fish and not enought plants, especialy easy pants, with fast grow, that biological filtration becomes crucial and the filter should contain mostly biological filtration media and should get a good amount of oxygen by the water so Nitrobacter sp. colony work well. So, it depend of many things.

From my experience, I started a 100 litters tank with an internal filter and soon I've got problems. I replaced it with an CristalProfi e901 with original filtration medium that are mostly sponges, but stil the water was not clear enought and still have problems with fish and shrimps. More than that, I had to clean it every month and each time there was an odor of hydrogen sulfide. It was clear that too much organic matter was entering the filter and staying there. Then I replaced all sponges from the baskets with Matrix and Siporax, keeping only the original sintetic balls on the bottom basket and top prefiltration sponces. Stil there were variations of the parametters of water. Finally, I added an internal Eheim prefilter (only one segment) and a Eheim micro-skimmer. From that time, no problem with water. Half of the plants are easy (Limnophila, Hygrophyla, Ludwigia and Rotala) the rest of its are Anubias, Pogostemon Helferi, Legenandra, ... . The fish are a little too many, also shrimps and snails, but looks like, in this formula, there are no pronlems. 

We should always remember that when the water is cristal clear this doesn't mean is clean! And for this we need biological filtration.

Cheers!


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## dw1305 (12 Jul 2017)

Hi all, 





Silviu Man said:


> But, if in the tank are many fish and not enought plants, especialy easy pants, with fast grow, that biological filtration becomes crucial and the filter should contain mostly biological filtration media and should get a good amount of oxygen by the water so Nitrobacter sp. colony work well.


There is some more discussion of this in <"Best way to cycle a second .....">.

cheers Darrel


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## alan'67 (12 Jul 2017)

Thank you for your posts guys.

When I posted this thread I thought my partners filter was ok and working well and that I had more of a problem.

Even though her filter is working ok and doing its job,I think a few minor changes to the intake, media and cleaning regime would be a major benefit in the long term.

There are very fine mesh sponges in the bottom of that filter that are always the first to get heavily covered in mulm/detritus.

Thank heavens for her healthy plant mass.

I always assumed plants major role in a tank was oxygenation of the water, I had no idea of their role in de-nitrification and ammonia control until I joined this forum. 

Thanks again chaps for your help.


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## dw1305 (13 Jul 2017)

Hi all,





alan'67 said:


> There are very fine mesh sponges in the bottom of that filter that are always the first to get heavily covered in mulm/detritus.


Yes, that is usually the problem, once the flow is impeded you either get the water tracking around the choked media altogether, or the whole water flow is slowed and it just follows the route of least resistance through the media.

The problem is that either way the majority  of the media is de-oxygenated. In the short term you may get a balance between aerobic nitrification and anaerobic denitrification, but you are always teetering on the brink of a failure of biological filtration, should the bioload increase or flow diminish.

In a <"Hamburg Matten Filter">, or a <"wet and dry trickle filter">, you can have both processes (nitrification, denitrification) running successfully, in the long term, because you have a large surface area exposed to air and/or oxygenated water where gas exchange can occur.

It is different in a canister filter, a finite amount of oxygen enters, and it can't be "topped up" in the filter. 





alan'67 said:


> Thank heavens for her healthy plant mass. I always assumed plants major role in a tank was oxygenation of the water, I had no idea of their role in de-nitrification and ammonia control until I joined this forum


For whatever reason there is a lot of resistance to the idea that plants make aquarium management easier, and any discussion of plants and cycling (on a most forums) usually ends up in a "flaming war". 

My suspicion is that there is a portion of the "ornamental fish trade" industry that doesn't want people to know that "plants and time" are all you need for a successful aquarium, and that is, at best, disingenuous about what their products do and don't do.

cheers Darrel


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## zozo (13 Jul 2017)

dw1305 said:


> For whatever reason there is a lot of resistance to the idea that plants make aquarium management easier, and any discussion of plants and cycling (on a most forums) usually ends up in a "flaming war".
> 
> My suspicion is that there is a portion of the "ornamental fish trade" industry that doesn't want people to know that "plants and time" are all you need for a successful aquarium, and that is, at best, disingenuous about what their products do and don't do.



You might be on the right track there.. Lately listened to an interview with some german guy at Myfish.org podcast, 40 years in the hobby and 25 years professional in the trade.. Stating 90% of the biological filtration occurs in the filter and even promoted the use of so called biological filter starters at each cleaning sesion. Didn't even mention plants for 1 minute..


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## dw1305 (13 Jul 2017)

Hi all, 





alan'67 said:


> I always assumed plants major role in a tank was oxygenation of the water, I had no idea of their role in de-nitrification and ammonia control until I joined this forum.


You might find this thread (and links) from earlier in 2017 worth reading: <"Do I need to cycle a planted....">, we have a lot of posts that cover the same area.





zozo said:


> .......40 years in the hobby and 25 years professional in the trade.. Stating 90% of the biological filtration occurs in the filter and even promoted the use of so called biological filter starters at each cleaning session. Didn't even mention plants for 1 minute.


That is still the default advice people are given on all sorts of platforms. 

Another strange thing is that people often quote <"Dr Tim Hovanec's"> scientific work on nitrification in the 1990's as justification for ammonia based "cycling", but if you actually look at Dr Hovanec's more recent  posts, he reviews his work in light of subsequent discoveries, and he also talks about the advantages of the planted tank. 

These are the Hovanec articles:
<"Aquatic plants and the nitrogen cycle">
<"Bacteria revealed"> & <"Water quality: a holistic approach">.

cheers Darrel


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## Silviu Man (13 Jul 2017)

The debate regarding "with or without plants" when speak about cycling the aqvarium is becoming redundant. People have this almost pathological tendency to complicate the things and to cross the line between sides. I am not a specialist in this domain but, from my bacground education, I know that a biotope is always chenged by biocoenosis, in most of the cases, in a good way. So, having a tank whitout plants will always be inferior to a tank with plants inside, in all circumstances. The nitrogen cycle, carbon cycle, parameters of the water, ... everything is changed in good by the plants. What was first revolution on the Earth, billion years ago, when there were only rocks and water? The evolution of the plants. What was the next one? The evolution of the animals. What is the most important in an ecosystem? To have all three together, in a ballanced system. This is so simple. Roots of the plants can host bacteria (look to soya and other kind of this plants : it have special vegetal formation, called nodosity, that host bacteria that can fix the nitrogen in the ground). Plants living under water are well known for the capacity to use certain elements from the water. There are experimental trials with plants that were cultivated in purified water and died! It's like when people will drink only pure water. Pure water is poison! An so on ...


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## zozo (13 Jul 2017)

Silviu Man said:


> What was first revolution on the Earth, billion years ago, when there were only rocks and water?



Who knows? I have the tendency to believe it was the Bacteria first, along came the photosyntesizing bactria which formed algae, followed by the chlorophytes which developd into hydrophytes and again macrophytes..  If all started and happend in marine inveronment, seems the most logical to me, marine hydrophytes are extremely rare and most are Algae and or chlorophytes.


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## Silviu Man (13 Jul 2017)

Yes, but this happened in the oceans. Then after all migrate in fresh water. And there were the real evolution of the plants, fish, amphibians, reptiles, mammalians... and finaly the stupid but beautiful bipeds!


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