# Denitrification



## symstep (Apr 3, 2019)

So I would like to have a discussion about denitrification regarding its understanding and what aspects are imperative. 
First off anyone replying to this thread understands denitrification is the conversion of nitrate to nitrogen gas through having a deep substrate that creates anoxic (No O2) conditions on the bottom level for the Heterotrophic facultative anaerobes to colonize. The HFA will use the nitrate as a oxidizing agent since no oxygen is present and this will result in the nitrate - nitrogen gas conversion. 
This process is a large part of removing the need for water changes and preventing most algae growth in freshwater aquariums. Some claims have been made of tanks going on 25+ years with no water changes and algae.

So there are a few things I would like to start this conversation off with...
1. Hydrogen sulfide. Within this deep substrate you will have a certain bacteria consuming carbon and sulfate and will in return create hydrogen sulfide. H2s is extremely toxic as everyone knows but I have read from multiply sources that H2s forming in anoxic zones will become neutralized (converted back to sulfate) in the presence of oxygen. From Wikipedia...
" Aeration
For concentrations of hydrogen sulfide less than 2 mg/L aeration is an ideal treatment process. Oxygen is added to water and a reaction between oxygen and hydrogen sulfide react to produce odorless sulfate[32]"
This indicates that if our tanks are properly aerated (which they should be regardless) then H2s should not be a concern. However, I happen to come across a post... "H2s to SO4 isn't a very efficient reaction without a catalyst metal of some sort." Is this simply not the case and the only limiting factor in this conversion is the oxygen due to such small amounts of H2s? Maybe this person is educated on a different matter and trying to apply it where it doesn't belong? or perhaps a source of iron would assist with this conversion?
2.The Heterotrophic facultative anaerobes need carbon. Carbon dosing is the stated option but if you have enough plants and fish then carbon dosing should not be necessary right? I have also heard that they do in fact need a source of iron to colonize but I have only heard this from one source.
3.Has anyone achieved this? If so Could you talk about your substrate, substrate critters, substrate height, your opinion on if iron is necessary etc.

All constructive replies are appreciated.


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## Quagulator (May 4, 2015)

symstep said:


> First off anyone replying to this thread understands denitrification is the conversion of nitrate to nitrogen gas through having a deep substrate that creates anoxic (No O2) conditions on the bottom level for the Heterotrophic facultative anaerobes to colonize. The HFA will use the nitrate as a oxidizing agent since no oxygen is present and this will result in the nitrate - nitrogen gas conversion.


That is not the only way to encourage anaerobic areas, you can achieve this running media in a reactor / sump that has deep pores, where anaerobic bacteria can thrive. 



symstep said:


> When this process is achieved it allegedly will remove the need for water changes and most algae growth in freshwater aquariums. Some claims have been made of tanks going on 25+ years with no water changes and algae.


The single best thing a planted tank can receive is a good water change regime. Proactively removing toxins, organics, excess fertilizers etc. Without replacing vital nutrients and minerals, we couldn't keep the tanks we do here on the forum. 

Nature is vastly up-scaled compared to our tiny glass boxes of water and plants. We can do our best to emulate it, but it's near impossible to achieve what happens in nature in our tanks. 

I'm all for removing NO3 if that is someone's goal, but it certainly does no eliminate the need for water changes.

This topic has been "discussed" here many, many, many times. The "discussions" never end up being peaceful, and never achieve anything - or solve a problem - or answer questions.


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## symstep (Apr 3, 2019)

Quagulator said:


> That is not the only way to encourage anaerobic areas, you can achieve this running media in a reactor / sump that has deep pores, where anaerobic bacteria can thrive.
> 
> 
> 
> ...


Yes creating a filtration system (canister filter or sump) with low flow where the nitrifying bacteria can deplete the oxygen so the second half of the filtration system can have anoxic conditions. I mainly wanted to discuss substrate tho, Still thank you for bringing this up for others.
Are you open to the idea that a water change regime is only necessary due to a lack of true balance? We need to "remove toxins" because we have not created the correct environment and so on? Therefore this could be a misconception. Considering On you tube you can find fully planted/lush aquariums that have not seen a water change in years. I did search Theplantedtank.net and didn't see a real discussion on this topic so thought I would start one, Sorry that I didn't see the threads you are referring to and sorry if that upset you.
''The "discussions" never end up being peaceful, and never achieve anything - or solve a problem - or answer questions.'' 
I can now see how this would happen since there apparently are people going around feeling the need to try and shut others down for simply a interest.  Thanks for the constructive reply.


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## Quesenek (Sep 26, 2008)

symstep said:


> Yes creating a filtration system (canister filter or sump) with low flow where the nitrifying bacteria can deplete the oxygen so the second half of the filtration system can have anoxic conditions. I mainly wanted to discuss substrate tho, Still thank you for bringing this up for others.
> Are you open to the idea that a water change regime is only necessary due to a lack of true balance? We need to "remove toxins" because we have not created the correct environment and so on? Therefore this could be a misconception. Considering On you tube you can find fully planted/lush aquariums that have not seen a water change in years. I did search Theplantedtank.net and didn't see a real discussion on this topic so thought I would start one, Sorry that I didn't see the threads you are referring to and sorry if that upset you.
> ''The "discussions" never end up being peaceful, and never achieve anything - or solve a problem - or answer questions.''
> I can now see how this would happen since there apparently are people going around feeling the need to try and shut others down for simply a interest.  Thanks for the constructive reply.


I did some research after seeing the video I'm sure you've also seen. 




The main issues I found from research is concerns for old tank syndrome from the lack of water changes and that planted tanks don't need anything to remove the nitrates since the plants use it to grow.

IMO I don't think many people have tried this method to the extent as say ocean aquarium. So I doubt much true information is out there.
This hobby is all about learning so TBH I would try it and use ocean aquarium as the reference.
The main things I see in their tanks is obviously the DSB, but also tons of fish and almost the limit of plants the tank can hold.
Along with that in one of Cory's videos of the Ocean Aquarium it shows how they use co2 and low/medium lighting to get optimal plant growth.


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## Maryland Guppy (Dec 6, 2014)

Typical planted aquarium includes NO3 dosing.
Accumulation of NO3 occurs if the phish load is heavy.
Many people, for some unknown reason like lots of phish? :grin2:
Many plants in my tank and the highest daily consumption that I can tell is about 3.5ppm NO3 per day.
Phish load in my tank provides no measurable NO3 with so few phish.

So what type of planted tank are you looking into?


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## symstep (Apr 3, 2019)

Quesenek said:


> I did some research after seeing the video I'm sure you've also seen. Ocean Aquarium
> 
> The main issues I found from research is concerns for old tank syndrome from the lack of water changes and that planted tanks don't need anything to remove the nitrates since the plants use it to grow.
> 
> ...


Hello there, thank you for the reply. 
Yes, ocean aquarium is probably the best example for this concept. I had a conversation with the guy (over the phone). When I asked about hydrogen sulfide, he said he just uses a chopstick to "pop the gravel every month or so, everything simple''. He uses a 5 inch substrate in all of his tanks but he recommends I use about 3 inches, all of his tanks have never seen a water change after being established and he doesn't test for anything except PH. Bonus note... Dr Kevin Novak (another denitrification guy) says the reason he has no algae in his tanks is because he has no nitrates. The OA guy said he has no algae because of his very low flow rate. He chooses low flow to combat algae because this is what he has observed in nature. Dudes a legend. 

Old tank syndrome is a great topic to bring up! Two aspects of OTS.
Water column - As water evaporates from your tank, minerals are left behind. Topping off the tank increases minerals to a toxic level. Previous fish slowly adapt but newly added fish will not survive. You could assume topping off with Ro water would combat this however, OA guy said he in fact uses tap water to top off. Said all he adds is a buffer for ph. So I would submit that the plants and fish utilize these minerals to prevent toxic build up. Everything is about balance. On the other end of this you could talk about mineral depletion. Dr kevin Novak argues that "all the plants need is the ammonia ion and a substrate to hold it", however this may be a discussion for another time. In terms of mineral depletion there would simply be proper dosing.
Substrate - There are stories of tank owners moving their hardscape around and soon after the livestock dies. This is because hydrogen sulfide built up and was released in a large amounts. Honestly this is the aspect I am trying to nail down. As I said in my original post, H2s is allegedly neutralized in the presence of oxygen, there is also bacteria that converts sulfide to sulfate. Perhaps these stories are where too much h2s is released at once and the oxygen doesn't have enough time to neutralize it? Perhaps to large of a anoxic zone? Plus they may be missing other important elements to this ecosystem. All the Ocean Aquarium guy had to say was what I quoted above, also I didn't want to take up too much of his time. So seemingly a good clean up crew, A proper substrate height, a good bacteria to bio load ratio (Nitrifying and Denitrifying bacteria within the deep substrate), releasing small amounts of h2s by force (popping) to prevent large build ups, plant roots bringing oxygen to the anoxic zones and having properly oxygenated water are the imperative elements to avoid Hydrogen sulfide poisoning? Also lets say if you are going to tear down or reorganize a lot of your tank... Take your fish out before hand. 

In terms of a salt water aquariums. Apparently salt water fish are far more sensitive, so denitrification seems to be wanted more. I am very new to this hobby and I can not efficiently speculate if success achieved in salt water can apply to fresh water. Considering (as you have said) the lack of information, Saltwater DSB success seems to be a good reference.

The ocean aquarium guys co2 method - Apparently this is a very old school method, and I love it! Everything is treated so simple. Dudes a legend

Thank you very much for your reply, Bringing information to the thread and relevant topics to discuss so visitors and ourselves can learn. I completely agree with you that this hobby is about learning. I will definitely try to achieve this true balance very soon. Just want to get as much information as possible before hand.


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## Quagulator (May 4, 2015)

symstep said:


> I will definitely try to achieve this true balance very soon. Just want to get as much information as possible before hand.


Make sure to start up a journal to track progress. Not many tanks around here running 0 NO3 and no water changes, would be a nice change of pace.


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## symstep (Apr 3, 2019)

Maryland Guppy said:


> Typical planted aquarium includes NO3 dosing.
> Accumulation of NO3 occurs if the phish load is heavy.
> Many people, for some unknown reason like lots of phish? :grin2:
> Many plants in my tank and the highest daily consumption that I can tell is about 3.5ppm NO3 per day.
> ...


Hello there. 
As for your tank, I kind of have a lot of questions haha
1. Can I see a picture?
2. How long has it been set up?
3. What exactly do you dose if you dose at all?
4. What has been this specific tanks experience with algae?
5. How often do you do water changes?
6. Do you gravel vac?
7. Type of gravel?
8. Height of gravel?
9. When did Nitrates start reading 0?


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## Quesenek (Sep 26, 2008)

symstep said:


> Substrate - There are stories of tank owners moving their hardscape around and soon after the livestock dies. This is because hydrogen sulfide built up and was released in a large amounts. Honestly this is the aspect I am trying to nail down. As I said in my original post, H2s is allegedly neutralized in the presence of oxygen, there is also bacteria that converts sulfide to sulfate. Perhaps these stories are where too much h2s is released at once and the oxygen doesn't have enough time to neutralize it? Perhaps to large of a anoxic zone? Plus they may be missing other important elements to this ecosystem. All the Ocean Aquarium guy had to say was what I quoted above, also I didn't want to take up too much of his time. So seemingly a good clean up crew, A proper substrate height, a good bacteria to bio load ratio (Nitrifying and Denitrifying bacteria within the deep substrate), releasing small amounts of h2s by force (popping) to prevent large build ups, plant roots bringing oxygen to the anoxic zones and having properly oxygenated water are the imperative elements to avoid Hydrogen sulfide poisoning? Also lets say if you are going to tear down or reorganize a lot of your tank... Take your fish out before hand.


I wonder if an army of Malaysian Trumpet Snails would do a good job of sifting the substrate to prevent the H2S from building up.
I've also heard conflicting information about H2S killing fish, Cory from the aquarium coop brings up the point that it builds up to toxic levels in the wild and supposedly it doesn't bother anything, however he also brings up that our aquariums are much smaller bodies of water then the ponds/lakes/rivers/seas in the wild so that could possibly be the reason it is toxic for us.


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## Edward (Apr 11, 2005)

Of course it can be done.
Most planted aquariums in the 60’s and 70’s were done like that. They were fully planted, had deep substrate, strong aeration, low light intensity and low fish load. No canister filtration, only sponges. Tap water was used to compensate for evaporation and mineral loss.

The system goal was to get things balanced. 
Tap top-ups replenished KH, Ca, Mg and other elements. Fish waste was used up by plants and also by substrate denitrification. Hormones and other organic substances were decomposed by bacteria and used up by plants. Long lighting periods of low light intensity grew plants and kept algae away. Often, pH dropped due to KH loss, or plants yellowed because of insufficient nitrogen. Harmful sulfur compounds were not forming where plant roots grew. 

They were cleaner and healthier than today’s chemical fertilizer bombs and tap water civilization contaminants. However, not all plants can live in these conditions and don’t expect many AGA aquascaping awards with it.


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## symstep (Apr 3, 2019)

Quesenek said:


> I wonder if an army of Malaysian Trumpet Snails would do a good job of sifting the substrate to prevent the H2S from building up.
> I've also heard conflicting information about H2S killing fish, Cory from the aquarium coop brings up the point that it builds up to toxic levels in the wild and supposedly it doesn't bother anything, however he also brings up that our aquariums are much smaller bodies of water then the ponds/lakes/rivers/seas in the wild so that could possibly be the reason it is toxic for us.


I think you are absolutely right. The clean up crew serves two purposes. One is "turning" the substrate and another is breaking down carbon for bacteria. As to what members to have in your crew, The MTS sound like the elite providing there isn't too much substrate agitation and interference with these bacteria. As for the H2s, I think the things I listed above may in fact be enough to not have to worry about it. 

Keep in mind all of this is like what Cory said. Its like baking with your grandmother .haha. Every tank and created environment is different.


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## DaveKS (Apr 2, 2019)

To me these are best managed in a controlled filter box environment with specific flow rates, specific prefilters grades and media specifically designed to do it in a precise way. 

To many ways for it to go wrong in gravel bed. Anyone who thinks a trumpet snail is going to sacrifice itself for the good of the tank by burrowing into a sulfide pocket is delusional. 

Setting up a external algae scrubber is a much simpler, safer solution all way around.


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## symstep (Apr 3, 2019)

Edward said:


> Of course it can be done.
> Most planted aquariums in the 60’s and 70’s were done like that. They were fully planted, had deep substrate, strong aeration, low light intensity and low fish load. No canister filtration, only sponges. Tap water was used to compensate for evaporation and mineral loss.
> 
> The system goal was to get things balanced.
> ...


Whats up edward, nice to interact with you again.

Also thank you! It is definitely possible. There is a lot of misconceptions in this hobby and it also comes down to what you are trying to accomplish. Have you been able to achieve this?



DaveKS said:


> To me these are best managed in a controlled filter box environment with specific flow rates, specific prefilters grades and media specifically designed to do it in a precise way.
> 
> To many ways for it to go wrong in gravel bed. Anyone who thinks a trumpet snail is going to sacrifice itself for the good of the tank by burrowing into a sulfide pocket is delusional.
> 
> Setting up a external algae scrubber is a much simpler, safer solution all way around.


What is this specifically designed media? Montmorillonite clay?
Would denitrification via sump still have the same danger since it flows directly back into the tank?
No one said anything about a snail sacrificing itself. It's presence in the tank among the other variables listed is what prevents these sulfide pockets in the first place. No one here is delusional. Apparently just rude.


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## Edward (Apr 11, 2005)

symstep said:


> Whats up edward, nice to interact with you again.
> 
> Also thank you! It is definitely possible. There is a lot of misconceptions in this hobby and it also comes down to what you are trying to accomplish. Have you been able to achieve this?


 Thank you. 
I have seen many aquariums designed the way it is described above and most were beautiful because they were long term projects, fully matured. Personally, I have had few set for number of years, minus the huge substrate layer. My plants always managed to keep NO3 low. Just give them PO4 boost and they will take the NO3 up. 

I know you are talking about substrate denitrification. Nevertheless, I should mention that I have tried canister filter denitrification and it worked wonders. I filled it with common red lava rock from Home Depot, and it was able to remove 3 – 4 ppm NO3 a day. The lava chunks must be > 1” in size for the bacteria to work because process is happening inside the porous rock.


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## Maryland Guppy (Dec 6, 2014)

symstep said:


> Hello there.
> As for your tank, I kind of have a lot of questions haha


1. Can I see a picture?
Pick from the end.








Pick of 1/2 front.









2. How long has it been set up?
Two years but changed out substrate 6 weeks ago. (6 weeks/same plants)

3. What exactly do you dose if you dose at all?
Macro & micros, CO2, 120PAR
Water column to never exceed 30ppm NO3 and .3ppm Fe

4. What has been this specific tanks experience with algae?
Substrate change from capped soil to BDBS horrible algae outbreak. (6 weeks ago)
Pearling Algae pic.








Fully recovered now.

5. How often do you do water changes?
14-18% weekly in 80G tank.

6. Do you gravel vac?
Yes if I uproot a large area of plants.

7. Type of gravel?
None, coal slag Black diamond blasting sand.

8. Height of gravel?
Two inches.

9. When did Nitrates start reading 0?
Never, I don't let it drop that low.
Past 12 weeks I've logged all dosing in the tank.
Daily consumption measurements to the best of my ability.
3.5ppm NO3 per day and .015 Fe per day.
This varies a bit from week to week but this is the maximum detected uptake.

10. I added this one, Phish Load. >
Includes 8 harlequin rasboras, 12 panda(small) Cory's, 2 flame tetras in an 80G.

My only Journal here is of this tank.


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## Surf (Jun 13, 2017)

> When this process is achieved it allegedly will remove the need for water changes and most algae growth in freshwater aquariums.


Denitrification will never eliminate the need for water changes. As water evaporates minerals concentrate in the water and every time you add more water you add more minerals. Unfortunately plants can only use a small number of minerals typically found in water. Eventually the level of total dissolved solids in water will get to high and plants and fish will die. Even if you use DI you will have a problem since fish food adds minerals. And if you are adding a fertilizer the minerals balance in the fertilizer will not match the mineral needs of the plants. This means unused minerals from the fertilizer will also build up in the water. 

So even if bacteria or plant keep you nitrates at zero you will have to do periodic water changes to prevent toxic levels of minerals.



> Yes, ocean aquarium is probably the best example for this concept.


Yes he does not do any deliberate water changes. But every time they they sell a fish or plant some of the water from the tank is also sold and lost. So if they sell a lot of fish from one tank They have to add quite a bit of water to compensate for the loss. No fish store can be an example of no water changes for this reason. Also fish store tanks are typically overstocked. That means a lot of fish waist entering the water. Most of the minerals in fish waist can be used by plants. So if you get the overstock / plant ratio right mineral buildup in the water might be very low. Also the water they add is very clean water comes from mountain steams in Yosemite national park.

So the owner of ocean aquarium has found a balance of fish waist to plants plus the water loss due to fish sails That works for him 

I do agrees that is it possible to have a tank with no fertilizer added to have low nitrate with good plant growth. but you still will need to do a water change. 

I did read of post about one persons koi pond. He admitted it was overstocked and a large portion of the pond was covered by water Hyacinth. He didn't say he was not doing water changes but he didn't have to do it often. So water changes only occurred during a periodic cleaning and plant removal. He also did state he was using a lot of fish food. I don't recall the exact number but it was measured in Kilograms, not grams, per day. And it wasn't an extremely large pond.


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## Quesenek (Sep 26, 2008)

Surf said:


> Denitrification will never eliminate the need for water changes. As water evaporates minerals concentrate in the water and every time you add more water you add more minerals. Unfortunately plants can only use a small number of minerals typically found in water. Eventually the level of total dissolved solids in water will get to high and plants and fish will die. Even if you use DI you will have a problem since fish food adds minerals. And if you are adding a fertilizer the minerals balance in the fertilizer will not match the mineral needs of the plants. This means unused minerals from the fertilizer will also build up in the water.
> 
> So even if bacteria or plant keep you nitrates at zero you will have to do periodic water changes to prevent toxic levels of minerals.
> 
> ...


How long would you say one could go without a water change?
I know on some walstad and low tech tanks water changes are done about every 6-8 months if I'm not mistaken, so would a large water change yearly be too little to prevent old tank syndrome or would it be achievable.


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## DaveKS (Apr 2, 2019)

@symstep I wasn’t trying to be rude, sorry if it came off that way.

What I was trying to point out is that a Inca snail is a oxygen breathing creature and as far as I know they only inhabit the aerobic areas of the gravel. If you know of some documented study that contradicts that I’d love to see it. One thing all living creatures have in common is intense desire to stay living.

The other part about specific media and building denitrification filters goes back decades, I was building them in late 90’s-2000’s. As @Edward alluded to in his post you can set up a better nitro filter in your canister. Why it’s better is because you can prefilter water hitting it and it stays stable, none of gunk gets in there and clogs your denitrifying media. 

Many designs for these types of filters can be found on internet. The specialized media like FilterPro BioHome, Seachem, Brightwell aquatics have been around for decades. 

Basic designs would be like couple 3” acrylic tubes hooked together with a a pvc U at bottom. Input you’d T off a canister or sump with .25-375” feed line w/ a valve. Input would be a filter with bonded filter pad followed by 5 micron felt. Rig up hooks so just hangs on edge of sump or tank. After about 2 wks letting it seed start taking sample and testing water, water on exit side still has some nitrate you slow flow down a bit so aerobic bacteria a start has more dwell time and depletes more oxygen and more of media goes anaerobic. You’ll find that once it’s seasoned and functioning properly you have can dial it in to what ever nitrate level you want simply by controlling the flow. Add a crapload more fish you can add a extra U shaped filter to handle it.

Canisters, if say you have Rena or other 6”ish filters, I’ll take a 4” tupperware tub, cut 3/8” hole bottom edge, opposite edge top cut a 3/4” hole, glue some fiberglass window screen to cover holes. Then get 1.5-2” lava rock and some .25-.5 lava rock. Arrange as many big chunks of lava as you can then fill about .5 to .75 of container with smaller grade lava. 

That container, 60% of water flow in canister will bypass it, micro-current that flows through it, give it about 3 months and it will settle in. For about $6 you can have a nice little nitro filter for a 30gal. 

Denitrifying is easy if you move it out of main tanks gravel bed, maintain a mostly aerobic gravel bed, let the tank/plants do best they can and then only if need (usually excessive fish load) set up de-nite stage after tank filter. 

Again I’m sorry if I came off as rude, not my intent. I started keeping aquariums almost 40 years ago, one of my best friends is a aquaculturist/biologist. The in tank flux of owner is one variable you can’t control, the processes governed by nature you can predict.


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## GrampsGrunge (Jun 18, 2012)

Maryland Guppy said:


> 1. Can I see a picture?
> Pick from the end.
> 
> 
> ...


Needs moar Phlame Tetras. You can never have enouph Phlame Tetras.


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## Edward (Apr 11, 2005)

Maryland Guppy said:


>


 Are the PVC rings under your plants for magnetic ring therapy?


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## Maryland Guppy (Dec 6, 2014)

They are ceramic, typical vendors sell plugs of plants wth the ceramic ring or lead strip wrapped around foam.
Just got into a habit of using to grow and farm after I acquired a huge lot of them for pennies.




The real magnet for such therapy is under the tank.
Electomagnet that require 480V and draws 70 amps.
Flux can be measured a few feet away.
I'm going to market as an algae buster!
It will go to market next February 30th. >>>


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## symstep (Apr 3, 2019)

Edward said:


> Thank you.
> I have seen many aquariums designed the way it is described above and most were beautiful because they were long term projects, fully matured. Personally, I have had few set for number of years, minus the huge substrate layer. My plants always managed to keep NO3 low. Just give them PO4 boost and they will take the NO3 up.
> 
> I know you are talking about substrate denitrification. Nevertheless, I should mention that I have tried canister filter denitrification and it worked wonders. I filled it with common red lava rock from Home Depot, and it was able to remove 3 – 4 ppm NO3 a day. The lava chunks must be > 1” in size for the bacteria to work because process is happening inside the porous rock.


Nice tipe to consider with the po4. What specific brand do you use?
Also the lava rock is a great thing to bring up! If you have a highly porous rock large enough, the nitrifying bacteria depletes the oxygen before the water reaches the core, therefore creating the anoxic environment for denitrification. Pretty cool.
Would you mind talking about a external filtration set up? It is my understanding that traditional canister filters are built for nitrification so there is excessive aeration in its design.

Bump: @Maryland Guppy
Thank you very much for putting so much time into your reply. I did originally misunderstand what you said. "Phish load in my tank provides no measurable NO3 with so few phish." I took that as No3 reading 0. Why do you think changing the substrate created the break out of algae? Also congrats on growing that forest!


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## symstep (Apr 3, 2019)

@Surf
Bump:


Surf said:


> "Denitrification will never eliminate the need for water changes.
> So even if bacteria or plant keep you nitrates at zero you will have to do periodic water changes to prevent toxic levels of minerals.
> Yes he does not do any deliberate water changes. But every time they they sell a fish or plant some of the water from the tank is also sold and lost. So if they sell a lot of fish from one tank They have to add quite a bit of water to compensate for the loss. No fish store can be an example of no water changes for this reason."
> 
> In terms of mineral build up, I feel like you are just repeating what I already said In my review of the two aspects of OTS. OTS is clearly avoidable tho without water changes. The ocean aquarium guy told me he has a 180 gallon at home that hasn't had a water change in 28 years. Others (non fish store) have achieved this as well. @Edward just said he himself has seen this done a few times. Denitrification is only a part of the puzzle to achieve this. I started this thread to work towards achieving this goal.


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## symstep (Apr 3, 2019)

@DaveKS No man, you are completely cool. I really appreciate the apology  In terms of the snail, that is our fault that we didn't really clarify that aspect. You are completely correct about snails not going into the anoxic zone (so i have learned). Say you create a substrate at 4 inches, the snails will visit the first 1-2 inches and "turn" the substrate. This will assist with overall compaction and aeration in the upper level so the H2s has a better chance to escape and become neutralized (A understanding based on my research). This in addition to the other elements mentioned might easily prevent H2s poisoning. The second advantage of the MTS is of course breaking down organic matter into finer particles for bacteria to use. I still would like to add that since the MTS reproduces so rapidly, isn't it possible that they will have a negative effect and disturb to much of the bacterial process?

That is excellent that you have experience with denitrification and I am very glad you made it to this thread. Based off what I have learned, A outside sump or canister specifically made could be more efficient. Yet still we do have the example of almost 30 years of only substrate. Also with outside denitrification I am still wondering why the potential of H2s would still not be a factor. 
If you would add new compartments to a canister filter, would that cause stress on the impeller or could you get away with it? Does iron play a important role in this process? I really appreciate your explanation of a cheap way to accomplish this but honestly you kind of lost me haha. I have seen a few videos of this and have seen it done for 20 dollars so I understand the general idea at least and I am much more into this idea then a plenum. however,I do want to explore the idea of the substrate. I am very curious if a lot of the things that are done in this hobby are somewhat complicated solutions to simple problems. Then again I have been in this hobby for less then a year. Thank you very much for your reply and I really appreciate your constructive input.


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## Edward (Apr 11, 2005)

symstep said:


> Denitrification is only a part of the puzzle to achieve this. I started this thread to work towards achieving this goal.


 That’s right, keeping NO3 in a set range is only one part. The other water parameters can be controlled as well, it all depends on how simple or complex you want to go. Higher complexity allows more light energy and CO2 and more plant species.


symstep said:


> Nice tip to consider with the po4. What specific brand do you use?


 Hagen Nutrafin PO4 test kit, although any other will do too, and for adding PO4, KH2PO4 compound. 


symstep said:


> Also the lava rock is a great thing to bring up! If you have a highly porous rock large enough, the nitrifying bacteria depletes the oxygen before the water reaches the core, therefore creating the anoxic environment for denitrification. Pretty cool.
> Would you mind talking about a external filtration set up? It is my understanding that traditional canister filters are built for nitrification so there is excessive aeration in its design.


 I don’t think there is aeration in canister filters, it would be noisy. So, it is pretty simple, remove all media and first fit a sponge and after that the lava rocks. The rocks need filtered water in order not to get covered in mulm. That’s it. 


symstep said:


> @Maryland Guppy
> Why do you think changing the substrate created the break out of algae?


 That’s what happens when conditions change, it is normal. Plants have to readjust to the new environment and they release nutrients which triggers algae which triggers snails. Then snail waste is taken back by the plants. 

BTW, the reason why you don’t see many threads about this style is because when some see it, they land on it and don’t stop arguing until the thread gets out of control and consequently locked by moderators. Some even suggested to amend the forum rules to prohibit this topic. Lunacy.


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## DaveKS (Apr 2, 2019)

A topic like this shouldn’t be off limits. 

Let your gravel and plants do what they do best. Plants and it’s roots in substrate via gas exchange actively try to stamp out anaerobic activity. They don’t want competition down there for nitrogen, they want it all. Redox potentials and cation exchange around root structure of plants are very high, that’s how they gather iron and other nutrients from substrate.

Some plants like giant Val once those strap like leaves hit water surface where they get all light and co2 they want there is a veritable super highway of gas being sent down to roots and nutrients being pumped up to leaves from roots. There will be no anaerobic activity around root zone no matter how hard you try to set one up. Inject C02 and you’ll effectively be super charging root zones for aerobic bacteria.


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## Maryland Guppy (Dec 6, 2014)

There are those topics that stir the forum up.

But in the end the proof is in the pudding.
Typically the one stirring the kettle can never provide proof or pictures of their success. >


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## symstep (Apr 3, 2019)

> That’s right, keeping NO3 in a set range is only one part. The other water parameters can be controlled as well, it all depends on how simple or complex you want to go. Higher complexity allows more light energy and CO2 and more plant species.


Thank you, I am glad you agree. I misspoke in my original post but it has been fixed. I feel like denitrification is the biggest part for me because I still don't have my head wrapped around the Hydrogen sulfide issue.



> I don’t think there is aeration in canister filters, it would be noisy. So, it is pretty simple, remove all media and first fit a sponge and after that the lava rocks. The rocks need filtered water in order not to get covered in mulm. That’s it.


Aeration in terms of its basic definition, to introduce oxygen. In nitrification the limiting factor is oxygen so canister filters have high and wide flow to introduce a lot of oxygen. I may have originally phrased it wrong, I am not sure. I assume still there would be some denitro going on at the end of the filtration, Also in the core of each lava rock (or equivalent) large enough. However, the nitro/denitro ratio should be closer to even so your off the shelf canister filter shouldn't achieve this yes? Of course it is relative to bio load and plant quantity tho.



> That’s what happens when conditions change, it is normal. Plants have to readjust to the new environment and they release nutrients which triggers algae which triggers snails. Then snail waste is taken back by the plants.


Thank you for breaking that down, I was unaware that the plants would release nutrients like that.



> BTW, the reason why you don’t see many threads about this style is because when some see it, they land on it and don’t stop arguing until the thread gets out of control and consequently locked by moderators. Some even suggested to amend the forum rules to prohibit this topic. Lunacy.


Yes, we all can have a closed mind based off of trusted information at times, I have been guilty of it as well. The idea of forbidding this topic is pretty crazy tho. This hobby is about learning and evolving independently and as a group. If we have a negative opinion or disbelieve then we voice it in a respectful way, then let others have their experience.


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## symstep (Apr 3, 2019)

> A topic like this shouldn’t be off limits.


Agreed!



> Redox potentials and cation exchange around root structure of plants are very high, that’s how they gather iron and other nutrients from substrate


Don't even get me started on CEC haha



> There will be no anaerobic activity around root zone no matter how hard you try to set one up.


I was aware of roots bringing oxygen to the lower substrate but didn't think of it being so severe it would prevent the denitro process. So you would submit that the height of the substrate would have to be based on the expected length of the root systems?


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## symstep (Apr 3, 2019)

Maryland Guppy said:


> There are those topics that stir the forum up.
> 
> But in the end the proof is in the pudding.
> Typically the one stirring the kettle can never provide proof or pictures of their success. >


Maybe one day i'll get there haha. But until then, if you haven't seen this channel you should. It actually is the most effort put into explaining this concept that I've seen so far.
Guy first did it with his turtle/cherry shrimp tank and now he is doing it with fish.






If you go to his channel you will find a explanation of this tank and then if you have like 2 hours, I would recommend watching his 7-8 part series on this subject. I would like to know what everyone thinks.


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## DaveKS (Apr 2, 2019)

symstep said:


> Agreed!
> 
> 
> 
> ...


Ever pulled up root system of a long established colony of crypts? Maybe a A. Crispus that’s been there a year or more? 3-4” down in gravel I know for sure, my old 65gal breeder was on frame stand where you could see bottom glass and use a flashlight to look at them. It was 3.5-4” gravel depth in back and there was no shortage of roots down that deep from crown type plants that were there long enough to grow that deep. Pretty sure there weren’t any anaerobic pockets anywhere those roots went. 

Never had a tank with any gravel over that deep though. 

Made mistake of trying a water hawthorn once. Once that 1st banana shaped floating leaf hit surface it went in super overdrive, within a month roots had fanned out to cover glass of 18” wide tank at bottom glass, growing 12+ new floating leaves a week. I couldn’t keep up with it. Nitrates and iron plummeted to zero in tank. Water top completely covered in those floating leaves. Had to get rid of it or would have completely smothered out all my other plants nor would I be able to afford keeping up with dosing. Would never try that again unless I had a 200gal tank I could devote entire end to it.

Apparently not only are tops of it’s leaves sunlight and co2 collectors that pump down to roots but bottom sides of floating leaves are also nutrient collectors as well. Can understand why it such a good pond plant though. That one plant could easily handle a 100gal tank with a fair sized fish load. Flowers are pretty also and have a nice smell to them.


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## Maryland Guppy (Dec 6, 2014)

GrampsGrunge said:


> Needs moar Phlame Tetras. You can never have enouph Phlame Tetras.


They are a neat phish, but weigh heavy on gluttony!
I started with 6, they were wild caught LFS informed me, only 2 survived.
They only receive them like twice a year and don't stay @ LFS for long.




symstep said:


> Maybe one day i'll get there haha. But until then, if you haven't seen this channel you should. It actually is the most effort put into explaining this concept that I've seen so far.
> Guy first did it with his turtle/cherry shrimp tank and now he is doing it with fish.


Not picking on you in any way and nor have you stirred the kettle.
We all of course like planted tank pics!!!

I attempted the video but my attention span gets weak after a few minutes.
Turtles can live in sewage and surface to breath periodically.
I will try again.

Back to denitrification:
I have a 75G tank that has lower light, I'm not really driving the plants hard.
It's more of a repository for species I don't wish to part with but keep them going.
It has a 4" PVC in tank filter in the corner.
Maybe I need larger lava rock in the PVC???
Been cycled for 4 years but does not break down NO3 to N.

If I turn up the lighting and CO2 it will just be another farm tank with excessive trimming.
It needs to be the "relax don't sweat it tank".


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## Edward (Apr 11, 2005)

Maryland Guppy, 
doesn’t this video explain where your unusually high NO3 plant uptake go?


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## Maryland Guppy (Dec 6, 2014)

Edward said:


> Maryland Guppy,
> doesn’t this video explain where your unusually high NO3 plant uptake go?
> 
> https://www.youtube.com/watch?v=_gYIZ_O_D_o


The nitrate consuming tank has no deep substrate nor does the 75G.
But if larger lava rock in the filter would work it could be a win.
I'll have to explain the 75G in more detail when I'm home.


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## Edward (Apr 11, 2005)

Maryland Guppy said:


> The nitrate consuming tank has no deep substrate nor does the 75G.


 In the video is substrate only 2”/5cm deep and it already removes nitrate.


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## Maryland Guppy (Dec 6, 2014)

All of my substrate was new BDBS about 1.5" deep 6-8 weeks ago.
That's in the tank I'm measuring fert uptake.

75G is 4 year old STS about 2" deep and it denitrifies nothing.
It does have cycled lava rock in a filter but no large pieces.
All lava rock is no larger than an inch.


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## symstep (Apr 3, 2019)

> Ever pulled up root system of a long established colony of crypts?


Unfortunately not to that extent. Now that you mention it, I did move a few crypts around not that long ago and a few of those roots were about 8 inches long. I went back and looked at some of the examples and the do have rooted plants so now I feel a little lost. Perhaps over estimating the potential of roots preventing anoxic conditions? 
As for you water hawthorn, do you recall a PH reading?


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## symstep (Apr 3, 2019)

> Not picking on you in any way and nor have you stirred the kettle.


Oh I know  Just wanted to clarify that I haven't tried this out yet and hopefully I will accomplish it. Also I had no idea I was getting into such a hot topic. As for your 75 gallon, I assume there is no NH3 and NO2 yes?


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