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Anoxic filtration.
A very interesting concept that has been quietly lurking around Cichlid-forum since approximately 2019 (from what I have found & seen in old posts, at least). Recently @Rockfella introduced this filtration process to us in this thread, in the Aquarium Setup section of the forum,


So, at the risk of the @dbblackdiamond post getting 'hijacked' by this ramping up discussion regarding Anoxic Filtration, I thought it best to bring the concept here in it's own thread.
(And yes El' Hefe, I fully expect the @SenorStrum experience to inform this post! Your scholarly approach and open-mindedness to these new and potentially beneficial concepts inform you sir.)
So....
Since @Rockfella posted up his remarkable results in implementing a DIY Anoxic Filtration system for his aquarium, I have been doing a 'deep dive' into that process and apparently have more questions than answers!
Basic info up front - Anoxic filtration is NOT anaerobic filtration. This process is NOT a simple de-Nitrator for your pond or aquarium. Nope, there seems to be quite a bit more going on with this concept than that..
Some questions as follows,
- 'Non-Clumping' Kitty Litter. It's all about that clay, apparently. There could be some interesting alternatives to non-clumping Kitty Litter out there using fired clay. For instance, why is Japanese Akadama not listed as viable?. Turface soil amendment (fired calcined clay) is another, along with this stuff,
Non-Clumping Kitty Litter encompasses a pretty big range and variety of products. And some products, as we all suspect... will turn into clay 'goo' if immersend in water for very long.
  • Pond applications of this process are producing some crazy results, with measured Nitrates being consistently consumed down to less than 10PPM. Phosphates also are being driven down to below 1PPM. Nice! But, how do those numbers translate when scaled down to aquarium-sized applications?
  • Maintenance. Keeping a Anoxic Filtration system running correctly apparently involves cleaning these things called 'Jap' (?) screens. What the heck are those? High density pre-filters? Then there is the replacement interval for the Non-Clumping Kitty Litter. itself. Does the system 'spontaneously combust or something if that Kitty Litter isn't replaced in a timely manner? Will bad things happen like in Activated Carbon if allowed to remain in the system too long? Then there was some sort of cleaning process I read that recommended using Wet/Dry vacs?!! The required maintenance and sustainability for this system seems to be all over the map. Has anyone standardized any part of this process yet?
  • The current DIY aspect of this process seems terrifying when confronted by some of the failure tales and testimonials expressed by those attempting to build and use this system. One involved Nitrite levels exploding when some unexpected portion of the Anoxic filtration failed. That could be a VERY serious problem if you invested in over $$$ in Wild Caught fish for your aquarium system.
  • KH and GH buildup. Inevitably there will less water changes conducted when successfully utilizing a system like this (that could be a VERY GOOD THING in some areas of the world where clean, fresh water is currently getting scarce). But, what happens if water evaporation in the aquarium system causes a steady buildup and increase in PH and water hardness values? Will that potential problem negatively affect the Anoxic filtration system? Is RO or distilled water going to be required as top-off water to replace evaporation in Anoxic aquarium filtration systems?
  • Dr. Kevin Novack seems to be the guru of Anoxic filtration. Has there been any studies of his work to validate or at least scientifically measure out those results, for possible general use implementation and wide-spread application?
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This thing seems promising. At least on a DIY level. All too often though, we have been lured down the DIY road of something fantastic, only to discover that the tradeoffs DO NOT add up to equal or exceed the benefits expected! I'd like to learn more about this, sure. But, a healthy amount of skeptiscm can (and usually is) a positive thing.
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So, let's talk Anoxic Filtration. :)
 
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Well, don't know much about this process other than following along the other thread. Seems interesting however there are other water parameters that come into play with regular water changes other than just nitrate levels. Hormone levels comes to mind, water buffering capacity, pH, buildup of elements like Ca, Mg etc. due to evaporation. Not sure if anoxic filtration is such a great idea when you consider the side effects that may occur.
 

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Alright, Y'all, this looks FUN! Thanks @Auballagh for the thread. It looks like I'm going to have to run back to the other thread, then do a bunch of reading. You may get something out of me in the next few days as these things take time.

However, I may be able to answer one question: In the researching of the building of my sump if found that the Aussies and folks who make pond filtration tend to use a particulate filtration media called "Japanese Mat Filter." What I also noticed is that because they're Aussies and (I guess...?) it doesn't sound so offensive to their ears, so they refer to it often as "Jap mat." My GUESS is that this is the "jap filter" being referred to here. Think of cheaper, tighter, Matala mat.
 

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Thank you @Auballagh for creating a new thread on this. My interest was definitely picked by @Rockfella so I spent most of last night doing some research on this process. For anybody interested in reading more, there is a gigantic thread on the SimplyDiscuss forum where folks share their experience: DIY "Anoxic Filtration System" eliminates nitrates? Anyone tried this? . It goes on for 52 pages, so it is quite the read.

One thing that came clear when reading it is that it is 100% NOT a replacement for doing water changes. As @Aussieman57 mentioned, there are other benefits to doing water changes than just lowering nitrates. Nitrates are sort of the canary in the coal mine, forcing us to do the water changes, but even with anoxic filtration process, water changes will need to happen. The reason why discus folks seem to be interested in this filtration process is that some of them are doing twice a day water changes and this process seems to allow them to move to doing water changes every 4 or 5 days instead.

What I found interesting in this filtration process is the elimination of both the ammonia and the nitrates at the same time using some fairly cheap and "readily" available materials, although simple clay-based cat litter doesn't seem to be so easy to find. :) I think this process, especially for fish that are very sensitive to nitrates (hello GBR!!!) could be interesting to try. My issue right now is that there doesn't seem to be a lot of empirical evidence that it truly works and definitely a lack of information on the sizing of the filtration system for a given number of fish/size of aquarium.
 

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Thank you @Auballagh for creating a new thread on this. My interest was definitely picked by @Rockfella so I spent most of last night doing some research on this process. For anybody interested in reading more, there is a gigantic thread on the SimplyDiscuss forum where folks share their experience: DIY "Anoxic Filtration System" eliminates nitrates? Anyone tried this? . It goes on for 52 pages, so it is quite the read.

One thing that came clear when reading it is that it is 100% NOT a replacement for doing water changes. As @Aussieman57 mentioned, there are other benefits to doing water changes than just lowering nitrates. Nitrates are sort of the canary in the coal mine, forcing us to do the water changes, but even with anoxic filtration process, water changes will need to happen. The reason why discus folks seem to be interested in this filtration process is that some of them are doing twice a day water changes and this process seems to allow them to move to doing water changes every 4 or 5 days instead.

What I found interesting in this filtration process is the elimination of both the ammonia and the nitrates at the same time using some fairly cheap and "readily" available materials, although simple clay-based cat litter doesn't seem to be so easy to find. :) I think this process, especially for fish that are very sensitive to nitrates (hello GBR!!!) could be interesting to try. My issue right now is that there doesn't seem to be a lot of empirical evidence that it truly works and definitely a lack of information on the sizing of the filtration system for a given number of fish/size of aquarium.
You will notice that thread has multiple opinions. For some it worked for some it did not. Some gave up on it after 1-2 years. The inventor states it is not an exacting science and multiple variables need to be in check for it to be in 100% working. I am no expert and after all the DIY I did my nitrates are still not down because my tap water has 40 ppm and I probably have failed to create anoxic conditions anywhere in my 2 aquariums. Despite this I firmly believe we should have clay somewhere in our tanks or sumps or anywhere possible. Will get into details later. Hobbyists who don't about AFS get very interested in it hoping to avoid water changes and I don't think it should be the biggest reason for anyone to choose AFS over conventional filters. Water changes can be reduced for sure I think.
 

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These are all good points. The promise of that anoxic filtration process, seems to offer benefits we can all use and enjoy.
Oh... but those details, though!
I mean sure, putting a little bag of non-clumping kitty litter in your hang on back filter may be all you need to exploit the Nitrate reducing effects of that clay. Or, it may be that the little bag offeres such a minuscule level of measured Nitrate reduction, that it just isn't worth it.
I dunno....
The length of TIME that the clay particles are emplaced and used as anoxic median in the system is troubling to me as well. I mean seriously, how long is the clay stuff usable? Until the beneficial bacteria inevitably covers al of the clay particles with a layer of bio-slime? When (like activated carbon) the stuff is just maxed out with all of the Nitrogenous stuff it can take in?
More details....
And lastly, is this something that benefits form a high flow rate (Canister or hang on back filter media). Or, will it work most efficiently as a sort of 'slow and go' process?
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Still waiting on El' Hefe to come back on this one. I'm sure he needed compressed air for the 'Deep Dive' on this technical sort of thing I'm sure he's doing ..... Standing by! :)
 
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I like the idea of removing the toxins rather than absorbing them and leaving them.
 
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Of all what I have gathered: A 30cmx30cmx20cm BCB (let's call it clay basket) can handle bioload of a adult Koi! Smaller baskets tend to have lesser anoxic zones. I tried my best to house biggest possible bcbs in my 7" tall overhead SUMP. Folks who have a proper SUMP should easily be able to use 1 or 2 8 lbs bag of Oil-dri and make a big BCB. Adult koi is 24-36" long. Our smaller fishes have a lot less bioload I would think. The doctor himself uses 4x4" and bigger round hand woven bcbs in canister filters.
Now as per the guide : Biocenosis baskets need very little maintenance because the life of the cat litter is indefinite. The inventor states he has used the same clay baskets for 20+ years. Water is made to move as fast as possible AROUND the basket not through it which is what happens in conventional filter system. The BCBs should ideally be in dedicated chamber in SUMP and mechanically filtered water should go around it.

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Another important feature to understand is that it’s only the ammonia molecules that are drawn into the baskets. Obviously, water floods into them when they are immersed, but after that, water doesn’t actually need to flow through them in order to filter out ammonia. The electrical charges in the centre of the basket only draw in ammonia molecules; they don’t draw in water molecules.

This directly addresses the second possible problem that can happen with some of the static types of conventional filter media – suspended particulates can clog the media and it will then become anaerobic. Critics, who haven’t taken the trouble to understand how the anoxic system works, often wrongly describe it as a “bog filter, full of nasty anaerobic bacteria”. They warn that the baskets are a breeding ground for parasitic bugs that can then spread to your fish. In fact the direct opposite is true.

Biocenosis baskets cannot clog because, if no water flows through them, there is no way that debris can be carried inside. On the other hand, if water flowing through conventional biofilters doesn’t have every speck of debris filtered out of it, there will always be the risk that sludge will settle inside and block the media. So, far from a biocenosis basket being a “bog filter”, it’s more likely that this label could be applied to a conventional system that hasn’t been kept sufficiently clean!

**
Anoxic Filtration (mankysanke.co.uk)

My BCBS look clean, all 3 of them.

I mean sure, putting a little bag of non-clumping kitty litter in your hang on back filter may be all you need to exploit the Nitrate reducing effects of that clay. Or, it may be that the little bag offeres such a minuscule level of measured Nitrate reduction, that it just isn't worth it.
I dunno....
The length of TIME that the clay particles are emplaced and used as anoxic median in the system is troubling to me as well. I mean seriously, how long is the clay stuff usable? Until the beneficial bacteria inevitably covers al of the clay particles with a layer of bio-slime? When (like activated carbon) the stuff is just maxed out with all of the Nitrogenous stuff it can take in?
More details....
And lastly, is this something that benefits form a high flow rate (Canister or hang on back filter media). Or, will it work most efficiently as a sort of 'slow and go' process?
Still waiting on El' Hefe to come back on this one. I'm sure he needed compressed air for the 'Deep Dive' on this technical sort of thing I'm sure he's doing ..... Standing by! :)
 

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I like the idea of removing the toxins rather than absorbing them and leaving them.
Thank you @DJRansome :)

A lot more happens inside the basket. The system if done right completes the nitrogen cycle. Nitrogen gas is released in the air. Man it is too detailed for me to type it all here and I don't understand it fully myself. The toxins eventually the basket :)
 

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I mean sure, putting a little bag of non-clumping kitty litter in your hang on back filter may be all you need to exploit the Nitrate reducing effects of that clay. Or, it may be that the little bag offeres such a minuscule level of measured Nitrate reduction, that it just isn't worth it.
I dunno....
And lastly, is this something that benefits form a high flow rate (Canister or hang on back filter media). Or, will it work most efficiently as a sort of 'slow and go' process?
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Still waiting on El' Hefe to come back on this one. I'm sure he needed compressed air for the 'Deep Dive' on this technical sort of thing I'm sure he's doing ..... Standing by! :)
Thank you @Auballagh :)
Little baskets won't do much. Making a biggest possible BCB in a canister will be way better. Water should go around the BCB as fast as possible without disturbing the clay. Clay does not degrade like regular biomedia. Does not need replacement. Some felt clay stopped working after 2 years. The high iron/laterite needs to be replenished every few years. Dr. Novak recommends injecting iron in the center of the basket.
 

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Well, don't know much about this process other than following along the other thread. Seems interesting however there are other water parameters that come into play with regular water changes other than just nitrate levels. Hormone levels comes to mind, water buffering capacity, pH, buildup of elements like Ca, Mg etc. due to evaporation. Not sure if anoxic filtration is such a great idea when you consider the side effects that may occur.
Clay seems to be the best friend of our beloved fish. They do good more than anything else. Heck we even have edible clay in my country.
 
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