Alternative Nitrate Reduction Method$

dasaltemelosguy

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I had the good fortune of limited access to an ichthyologist and marine biologist who operate an LFS here in Southern California and work at an aquarium in San Diego. We began what became almost a full year of informal but largely quantified gatherings of data on nitrate reduction techniques and efficacy. Some is unfortunately anecdotal but much of it was quantified in a way that some Aquarists may find helpful.

Filtration options for nitrate reduction, can be difficult, expensive and surprisingly fragile. The aerobic bacteria consume ammonia and nitrite, the anaerobic consume nitrates...but the latter are fussy eaters! Nitrate reduction via filtration often has little to no effect as it can take 6-8 months to build a sufficient anaerobic colony to actually reduce nitrates meaningfully...and this requires enormous volumes of media.

Far more than would be need for the rest of the nitrogen cycle!

We began cultivating anaerobic colonies in pond media and found the amount of media required for an efficacious anaerobic colony to be far greater than we hoped for or that would be practical. Nitrate reduction via anaerobic colony filtration is VERY inefficient and requires voluminous amounts of media for meaningful nitrate reduction.

One example being a massive 900gph canister filter with some 6L of media capacity and TWO of these filters with a total of 12L of media, still cannot support enough media for effective anaerobic colonies for a ‘typically stocked 125G cichlid tank’ for significant nitrate reduction.

One such filter has ample amounts of flow and media capacity for aerobic colonies (the bacteria that removes ammonia and nitrite), but for anaerobic colonies (the bacteria that consumes nitrates), you’d need FOUR such canisters (25L pond media or similar) to have enough media to reduce nitrates just 10PPM!

I also find anaerobic colonies are MUCH more fragile than aerobic such that they are easily killed by accident. I cannot quantify this but I have experienced the results and I’ve yet to successfully neutralize rechargable media well enough to NOT reduce the anaerobic colony count.

In fact, re-using rechargable (with bleach) media that was then soaked in dechlorinator for 24 hours still killed off almost 6 out of 8 months growth of the anaerobic colony! Yet the aerobic bacteria saw no drop in population.

(I believe Pond Guru mentions a similar test and results in some of his videos)

I went a different route after months of trying to get meaningful nitrate reduction in the filters. Instead of trying to get nitrate reduction with more filters or additional media, I tried Epipremnum/riparian plants: roots in the water, leaves out the top.

I replaced part of the glass with plastic lighting grid to support the roots and stalks:

bamboo grid top close 7572.jpg


Bamboo Grid 12572.jpg


I had initially added Epipremnum/riparian plants primarily because I thought it was pretty. I had NO idea the degree of nitrate reduction this would have. I was not prepared for the results.

One tank was a 120G heavily stocked with adult, SA cichlids, 12 Acaras, 2 large plecos and 8 Severums in this case:

Sev2Oscar Rear.jpg


A 2nd tank, a 125G was heavily stocked with larger fishes, plecos, Oscars and pacu’s (I’ve since had to rehome my beloved pacu’s as they were approaching 18″ in length!):

Sev2OscarRear close.JPG


The following are before and after a two week period with Epipremnum/riparian plants above in these tanks:

-The 120 typically reached circa 40ppm after a week when I’d do a WC.

-Inside of two weeks, the 120G at 40ppm has yet to ever reach 10ppm.


-The 125 was more problematic with nitrates I was having enormous difficulty controlling. This tank (prior to rehoming the pacu’s) would typically reach 80ppm-160ppm inside of 1 week (!) such that I was performing 2-3 WC’s/week until I could rehome them!

-Same time frame, the circa 80ppm-160ppm tank had still not risen to even 30ppm!


There was also little question that the nitrates fell further still once we installed grow lights. This is not shown in the pictures as they were not installed yet;

-With the lights on 12-16 hours/day or so, the 120 dropped from 10ppm to 5ppm, or possibly 0, it’s that difficult to read.

-The 125 dropped to 10ppm and has yet to ever reach 20ppm since adding the grow lights.


There are two properties to be mindful of in play and it’s entirely photosynthetic. Terrestrial plants use more nitrates vs ammonia than aquatic plants due to the availability of greater photosynthetic energy. They evolved with leaves under the sun, and in turn, enjoy more light energy which allows them to directly process nitrates more efficiently. Aquatic plants first absorb ammonia and will attempt to expend more energy if need be photosynthetically to consume nitrates so long as enough light energy is present.

The latter is more efficacious when the lighting is stronger which is not optimal for most aquatic plants nor the fish as the efficacy of nitrate consumption is quite related to the amount of light the plants are exposed to. Naturally submerged plants would see diminished light and evolve accordingly. But terrestrial plants evolved for this environment.

I used pothos and monstera in my tanks as well as Lucky Bamboo in a 3rd tank. A single, $20 pothos plant has virtually eliminated nitrates in the 120 and the same with the 125 since rehoming the pacu’s:

Sev2Oscar.jpg


The big (literally and numerically) surprise was the dracaena or Lucky Bamboo. The pothos reveled its full potential in under 2 weeks. Lucky Bamboo took longer to display results, about 4 weeks vs only 2 weeks for pothos, but the 'bamboo' in particular has reduced nitrates so greatly, I’m not confident I can measure any at all with a liquid test kit now:

Bamboo Side-172.jpg


In my disbelief, I went out and bought a fresh liquid test kit to see if mine had spoiled but again, NO nitrates! A fully stocked SA cichlid tank with 0 nitrates? It sounded crazy to me but of all of the plants I’ve tried, Lucky Bamboo is the nitrate eating champion thus far.

What the image does not show is their growth. In case you were wondering where all those nitrates went, the Lucky Bamboo has grown from 24" stalks to now 6' in height!

Bamboo Close72.jpg


One topic that will no doubt be raised and rightfully so, is the toxicity of certain plants and their utility in an aquarium. In particular, pothos is known to be toxic to some animals.

But in truth, nearly ALL Epipremnum/riparian plants, even monstera have this same toxin throughout the entire plants, leaves and roots. The toxin is Calcium Oxalate. It's not actually toxic to fish due to it's insolubility as it requires a very acidic environment to leach into the water as it becomes soluble at PH = 4.5. Above 4.5 it's remains crystalline which is the actual issue for dogs and cats as the crystals can cause irritation or sores in mammals.

But even if it contains any toxins, if your PH is above 4.5, it cannot leach into the water as it's insoluble.

Admittedly we performed no tests on this as the LFS owners have actually not seen an incident of toxicity with Epipremnum/riparian plants in any of their aquariums nor their customers. In truth, even if it were toxic, the leaching ability can only occur when the plant is cut AND the PH is below 4.5.

I don't bother with rooting cuttings. I just wash the roots and let them drape into the tank through the plastic lighting grid. Of all my fishes, only the Severums eat the roots (and the plecos eat the algae on the roots). I have seen my Severums eat the roots for years without incident:

ebas72.jpg


While it may not appeal to everyone, a single Epipremnum/riparian plant can remove virtually all the nitrates directly from the water column if given enough time (weeks). I wish this could be more extensive and exhaustive but given the limitations of our testing, one thing I can say with confidence is there's no greater nitrate reduction one can get for a freshwater tank for $20!
 
Thanks for your well written explanations and suggestions on how to reduce nitrate.

By the way, I was wondering if you have a lot of fast growing plants that can remove the ammonia, then probably you will have less nitrate as you will skip these stages of ammonia-> nitrite-> nitrate.
But I guess if you have many large fish that produce a lot of ammonia, then probably this won't be possible.
Just my thought...
 
Nice write up. The only thing I would have liked to see is the pacus kept in the tank while the plants were being used so we could see how much the plants could remove. Pacus eat lots and produce lots of waste so removing them would have allowed the nitrates to come down with water changes. If the plants had been run with pacus in the tank for several months, it would have given more data. But overall, nicely written and plants are great at cleaning things up :)
 
@dasaltemelosguy - thank you for this information, especially the bit about the toxin not being of concern for fish.

I have a philodendron in my tank, zero nitrates, but have always been a little wary of the toxin issue, especially if I needed to cut the roots back a bit.

@Guyb93 this will be perfect reading for you and negates my warning that the roots might have toxins when first cut 🙂
 
I had the good fortune of limited access to an ichthyologist and marine biologist who operate an LFS here in Southern California and work at an aquarium in San Diego. We began what became almost a full year of informal but largely quantified gatherings of data on nitrate reduction techniques and efficacy. Some is unfortunately anecdotal but much of it was quantified in a way that some Aquarists may find helpful.

Filtration options for nitrate reduction, can be difficult, expensive and surprisingly fragile. The aerobic bacteria consume ammonia and nitrite, the anaerobic consume nitrates...but the latter are fussy eaters! Nitrate reduction via filtration often has little to no effect as it can take 6-8 months to build a sufficient anaerobic colony to actually reduce nitrates meaningfully...and this requires enormous volumes of media.

Far more than would be need for the rest of the nitrogen cycle!

We began cultivating anaerobic colonies in pond media and found the amount of media required for an efficacious anaerobic colony to be far greater than we hoped for or that would be practical. Nitrate reduction via anaerobic colony filtration is VERY inefficient and requires voluminous amounts of media for meaningful nitrate reduction.

One example being a massive 900gph canister filter with some 6L of media capacity and TWO of these filters with a total of 12L of media, still cannot support enough media for effective anaerobic colonies for a ‘typically stocked 125G cichlid tank’ for significant nitrate reduction.

One such filter has ample amounts of flow and media capacity for aerobic colonies (the bacteria that removes ammonia and nitrite), but for anaerobic colonies (the bacteria that consumes nitrates), you’d need FOUR such canisters (25L pond media or similar) to have enough media to reduce nitrates just 10PPM!

I also find anaerobic colonies are MUCH more fragile than aerobic such that they are easily killed by accident. I cannot quantify this but I have experienced the results and I’ve yet to successfully neutralize rechargable media well enough to NOT reduce the anaerobic colony count.

In fact, re-using rechargable (with bleach) media that was then soaked in dechlorinator for 24 hours still killed off almost 6 out of 8 months growth of the anaerobic colony! Yet the aerobic bacteria saw no drop in population.

(I believe Pond Guru mentions a similar test and results in some of his videos)

I went a different route after months of trying to get meaningful nitrate reduction in the filters. Instead of trying to get nitrate reduction with more filters or additional media, I tried Epipremnum/riparian plants: roots in the water, leaves out the top.

I replaced part of the glass with plastic lighting grid to support the roots and stalks:

View attachment 146215

View attachment 146216

I had initially added Epipremnum/riparian plants primarily because I thought it was pretty. I had NO idea the degree of nitrate reduction this would have. I was not prepared for the results.

One tank was a 120G heavily stocked with adult, SA cichlids, 12 Acaras, 2 large plecos and 8 Severums in this case:

View attachment 146220

A 2nd tank, a 125G was heavily stocked with larger fishes, plecos, Oscars and pacu’s (I’ve since had to rehome my beloved pacu’s as they were approaching 18″ in length!):

View attachment 146221

The following are before and after a two week period with Epipremnum/riparian plants above in these tanks:

-The 120 typically reached circa 40ppm after a week when I’d do a WC.

-Inside of two weeks, the 120G at 40ppm has yet to ever reach 10ppm.


-The 125 was more problematic with nitrates I was having enormous difficulty controlling. This tank (prior to rehoming the pacu’s) would typically reach 80ppm-160ppm inside of 1 week (!) such that I was performing 2-3 WC’s/week until I could rehome them!

-Same time frame, the circa 80ppm-160ppm tank had still not risen to even 30ppm!


There was also little question that the nitrates fell further still once we installed grow lights. This is not shown in the pictures as they were not installed yet;

-With the lights on 12-16 hours/day or so, the 120 dropped from 10ppm to 5ppm, or possibly 0, it’s that difficult to read.

-The 125 dropped to 10ppm and has yet to ever reach 20ppm since adding the grow lights.


There are two properties to be mindful of in play and it’s entirely photosynthetic. Terrestrial plants use more nitrates vs ammonia than aquatic plants due to the availability of greater photosynthetic energy. They evolved with leaves under the sun, and in turn, enjoy more light energy which allows them to directly process nitrates more efficiently. Aquatic plants first absorb ammonia and will attempt to expend more energy if need be photosynthetically to consume nitrates so long as enough light energy is present.

The latter is more efficacious when the lighting is stronger which is not optimal for most aquatic plants nor the fish as the efficacy of nitrate consumption is quite related to the amount of light the plants are exposed to. Naturally submerged plants would see diminished light and evolve accordingly. But terrestrial plants evolved for this environment.

I used pothos and monstera in my tanks as well as Lucky Bamboo in a 3rd tank. A single, $20 pothos plant has virtually eliminated nitrates in the 120 and the same with the 125 since rehoming the pacu’s:

View attachment 146222

The big (literally and numerically) surprise was the dracaena or Lucky Bamboo. The pothos reveled its full potential in under 2 weeks. Lucky Bamboo took longer to display results, about 4 weeks vs only 2 weeks for pothos, but the 'bamboo' in particular has reduced nitrates so greatly, I’m not confident I can measure any at all with a liquid test kit now:

View attachment 146223

In my disbelief, I went out and bought a fresh liquid test kit to see if mine had spoiled but again, NO nitrates! A fully stocked SA cichlid tank with 0 nitrates? It sounded crazy to me but of all of the plants I’ve tried, Lucky Bamboo is the nitrate eating champion thus far.

What the image does not show is their growth. In case you were wondering where all those nitrates went, the Lucky Bamboo has grown from 24" stalks to now 6' in height!

View attachment 146224


One topic that will no doubt be raised and rightfully so, is the toxicity of certain plants and their utility in an aquarium. In particular, pothos is known to be toxic to some animals.

But in truth, nearly ALL Epipremnum/riparian plants, even monstera have this same toxin throughout the entire plants, leaves and roots. The toxin is Calcium Oxalate. It's not actually toxic to fish due to it's insolubility as it requires a very acidic environment to leach into the water as it becomes soluble at PH = 4.5. Above 4.5 it's remains crystalline which is the actual issue for dogs and cats as the crystals can cause irritation or sores in mammals.

But even if it contains any toxins, if your PH is above 4.5, it cannot leach into the water as it's insoluble.

Admittedly we performed no tests on this as the LFS owners have actually not seen an incident of toxicity with Epipremnum/riparian plants in any of their aquariums nor their customers. In truth, even if it were toxic, the leaching ability can only occur when the plant is cut AND the PH is below 4.5.

I don't bother with rooting cuttings. I just wash the roots and let them drape into the tank through the plastic lighting grid. Of all my fishes, only the Severums eat the roots (and the plecos eat the algae on the roots). I have seen my Severums eat the roots for years without incident:

View attachment 146225

While it may not appeal to everyone, a single Epipremnum/riparian plant can remove virtually all the nitrates directly from the water column if given enough time (weeks). I wish this could be more extensive and exhaustive but given the limitations of our testing, one thing I can say with confidence is there's no greater nitrate reduction one can get for a freshwater tank for $20!
Brilliant post! Data on pothos toxicity of particular interest to me; knew they were safe, but not precisely why. Like how you placed cuttings directly though the grid. I’d been rooting mine first & then struggling with attaching them to thick rimmed tank.
 
Nice write up. The only thing I would have liked to see is the pacus kept in the tank while the plants were being used so we could see how much the plants could remove. Pacus eat lots and produce lots of waste so removing them would have allowed the nitrates to come down with water changes. If the plants had been run with pacus in the tank for several months, it would have given more data. But overall, nicely written and plants are great at cleaning things up :)
Thank you. I hope some find it of value. We did unfortunately introduce an unwanted variable. My fault as I greatly underestimated the Pacu's rate of growth (I thought it was Oscar-esque but they grew from 4" to 18" in under 6 months!) and I had to rehome them mid-test cycle! However the relative data for control purposes is still valid such that the nitrate drop in the 125 was about 70%-80%, even when the Pacu's were present but of course the base number was higher. Serious eaters and poopers to be sure!
 
Such a good thread thankyou for posting it :) You've cleared up so much for me on this and so interesting about the toxicity only being soluable in low ph.

One thing I've noticed is that you dont have any aquatic plants growing in the tank? Is this because of the fish you keep like the Severums and Pacus? Do you know what the make of those plants are? I'm after some to use in a tank temporarily while I move it around a bit.

In terms of your nitrates do you have any nitrate in your tap water? For me this is the main issue though I may be able to get around this better soon as I have installed an RO system - though terrified of transitioning... but either way I'm going to be keeping big fish again soon and want to get a better idea of this :)

Wills
 
That's really nice of you to say, thank you.

And you're right on both counts. With the Severums and Pacu's, I simply could not find an aquatic plant they would not eat to the stem (Severums) or totally destroy (Pacu's). Similarly the large Oscar in the 125 will literally yank up any I've planted so after a year of murdering plants, I gave up. The Oscar DOES try to move the dracaena but to no avail!

Our local (Los Angeles) water seems to have no measurable nitrates, at least insofar as the API Liquid Test kit can reveal.

I can tell you that we planted anubia's and sword's which were growing well before the fish decided otherwise!

The LFS folks showed me an interesting example which I'm embarrassed to have forgotten the chemistry of (I was a chemical physicist in the 1970s so 'duh' on my part!) but free ammonia always exists simultaneously with the stable ammonia (ammonium) and/or nitrites at any given moment such that before some of it is processed by the BB, it's available for plants as it's in the water column vs the media so it's more readily accessible to aquatic plants.

This I was told provides more than enough ammonia for aquatic plants provided their other essentials are met. The terrestrials don't compete with ammonia as food as they primarily absorb nitrates.

I imagine it may be possible to deplete the nitrates so greatly it could starve plants and algae. In my situation, the plants gets always got destroyed but I still have a good deal of diatoms so I suppose there's enough nitrates to go around!
 
That's really nice of you to say, thank you.

And you're right on both counts. With the Severums and Pacu's, I simply could not find an aquatic plant they would not eat to the stem (Severums) or totally destroy (Pacu's). Similarly the large Oscar in the 125 will literally yank up any I've planted so after a year of murdering plants, I gave up. The Oscar DOES try to move the dracaena but to no avail!

Our local (Los Angeles) water seems to have no measurable nitrates, at least insofar as the API Liquid Test kit can reveal.

I can tell you that we planted anubia's and sword's which were growing well before the fish decided otherwise!

The LFS folks showed me an interesting example which I'm embarrassed to have forgotten the chemistry of (I was a chemical physicist in the 1970s so 'duh' on my part!) but free ammonia always exists simultaneously with the stable ammonia (ammonium) and/or nitrites at any given moment such that before some of it is processed by the BB, it's available for plants as it's in the water column vs the media so it's more readily accessible to aquatic plants.

This I was told provides more than enough ammonia for aquatic plants provided their other essentials are met. The terrestrials don't compete with ammonia as food as they primarily absorb nitrates.

I imagine it may be possible to deplete the nitrates so greatly it could starve plants and algae. In my situation, the plants gets always got destroyed but I still have a good deal of diatoms so I suppose there's enough nitrates to go around!
Look what you inspired today! I cut the bottom from a plastic pot & hung it from the rim with a S hook. Will do cuttings through the grid too
 

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With high nitrates in my well water back when, I spent a fair amount of time and energy in My Nitrate Fight. For most hobbyists, taking steps for Lowering Aquarium Nitrates and in the end, fast growing floating plants that are ammonia sponges converting ammonia into plant tissue and routine periodic partial water changes of sufficient volume are all that's needed to keep the water quality high. :)

EDIT: As the post suggests, be wary of the marketing hype of bio-media manufacturers claiming that their media will culture anoxic/anaerobic bacteria to reduce nitrates. It's largely rainbows and unicorns! Plants are our best investment to better process ammonia and in some cases nitrates. And remember there's typically no such thing as too much clean, fresh water so do routine, periodic, partial water changes of sufficient volume for the highest possible water quality.
 
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Look what you inspired today! I cut the bottom from a plastic pot & hung it from the rim with a S hook. Will do cuttings through the grid too
Wow! That looks hauntingly beautiful! I love the way you have the roots draping through the water as the grassy looking plant (forgive my ignorance, I can't figure out what that is) drifts the opposite direction forming an inverse arch. And on top, wow! So you fed the pothos through the grid and created a hanger for the vines? In a word, WOW! Fire up that Canon! :drinks:
 
Thanks! I didn’t use the grid for this pothos, but I have a cut section along the tank rear that will be used for “bamboo.” The pothos in the pic was washed thoroughly to remove soil & then placed in a planter with the bottom removed & attached to the tank with a S hook. Pothos Jumpstart.
 
Ooh, that's a really good idea. You hung them and fed the roots into the water? That would allow for even more as hangings or additional types of plants. I think you've just started something!
 
Your inspiration! 🙏🏻 Yes, all roots hanging into water. Just watching goldfish nibbling at them while riding stationary bike next to tank. Guess it’s actually nosing not nibbling. I was thinking of placing anthurium the same way, but doubt I meet their light requirements.
 

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