Is expensive bio media worth it?

[MichaelJ]

Hi @dw1305

Perhaps you could shed some light (!) on the following statement made by Diana Walstad in her book, Ecology of the Planted Aquarium:

"the majority of aquatic plants - given a choice - greatly prefer ammonium. This fact is critical to fish health and aquarium functioning".

Hi @jaypeecee What page is that on ? ... I want to read the context where this statement was made - not that I doubt its true... my guess would be that it's just easier for the plants to get the Nitrogen through NH4 rather than NO3, but I surely do not know for sure.

Cheers,
Michael

 

[dw1305]

Hi all,

the majority of aquatic plants - given a choice - greatly prefer ammonium. This fact is critical to fish health and aquarium functioning

my guess would be that it's just easier for the plants to get the Nitrogen through NH4 rather than NO3,

They do, due to the kinetic advantages of ammonium (NH4+) uptake over nitrate (NO3-) uptake. I honestly don't think what form of fixed nitrogen plants preferentially take up is <"that relevant">.

I think Diana Walstad put it in her book because, at the time, the prevailing view amongst fish-keepers (but not scientists) was that <"plants didn't take up ammonia, only nitrate"> and therefore plants weren't of any practical importance in biological filtration, because they didn't take up ammonia, just nitrate.

The argument was then that the damage had already been done before the plants removed the "relatively benign" nitrate and it was only the Ammonia Oxidising Bacteria (AOB) <"Nitrosomonas that counted in ammonia oxidation">.

cheers Darrel

 

[Vsevolod Stakhov]

"the majority of aquatic plants - given a choice - greatly prefer ammonium. This fact is critical to fish health and aquarium functioning".

As far as I remember, Tom Barr mentioned (p. 11) that plants prefers ammonium and do not consume nitrates when there is enough ammonium in the water.

On the other hand, higher plants store nitrogen in the form of NO3- in the intra-cells vacuoles, so it arises the question if a plant can oxidise ammonia to NO3 (I mean if it has the appropriate enzymes for that). I know that nitrogen is a mobile element and it can be transferred in several organic and ionorganic forms within a plant, I'm mostly curious about if an NH4+ to NO3- conversion is ever possible within plants.

 

[jaypeecee]

What page is that on ? ... I want to read the context where this statement was made - not that I doubt its true... my guess would be that it's just easier for the plants to get the Nitrogen through NH4 rather than NO3, but I surely do not know for sure.

Hi @MichaelJ

No problem. The quoted statement is on p108 of the Third Edition.

JPC

 

[jaypeecee]

Hi @dw1305

Many thanks for your reply.

The reason for my labouring the point is this - I wondered if aquatic plants were being sustained on ammonium only and that they may not uptake significant nitrate. The combination of this and the end-product of nitrification (i.e. nitrate) may result in (rapid?) build-up of nitrate in the water column. Only by running tests on aquariums would we be able to quantify this. Unless someone's already been there, done that and got the T-Shirt! Now, some people will accuse me of overthinking this. But, sorry folks, that's what I used to get paid for!

JPC

 

[jaypeecee]

Tom Barr mentioned (p. 11) that plants prefers ammonium and do not consume nitrates when there is enough ammonium in the water.

Hi @Vsevolod Stakhov

The graph presented on page 11, fig 3 appears to be identical to the graph on page 107 of Diana Walstad's book. Just thought this was worth mentioning.

JPC

P.S. it seems ages ago that you and I got those water tests done in Moscow.

 

[Jaseon]

The question doesnt make sense to me as what's expensive may be relatively cheap to someone else.

 

[Maf 2500]

The reason for my labouring the point is this - I wondered if aquatic plants were being sustained on ammonium only and that they may not uptake significant nitrate. The combination of this and the end-product of nitrification (i.e. nitrate) may result in (rapid?) build-up of nitrate in the water column. Only by running tests on aquariums would we be able to quantify this. Unless someone's already been there, done that and got the T-Shirt! Now, some people will accuse me of overthinking this. But, sorry folks, that's what I used to get paid for!

JPC

I don't understand this comment, I hope I am not being thick and missing something obvious. Surely the established practice of dosing nitrates into the water column via EI, or other nutrient regimes, and said practice not causing excess nitrate problems proves that aquatic plants uptake nitrates? I don't think there is any scientific doubt that aquatic plants can uptake nitrates; as @dw1305 points out above aquatic plants have the capacity to uptake either ammonium or nitrate depending on what is available.

 

[MichaelJ]

I don't understand this comment, I hope I am not being thick and missing something obvious. Surely the established practice of dosing nitrates into the water column via EI, or other nutrient regimes, and said practice not causing excess nitrate problems proves that aquatic plants uptake nitrates? I don't think there is any scientific doubt that aquatic plants can uptake nitrates; as @dw1305 points out above aquatic plants have the capacity to uptake either ammonium or nitrate depending on what is available.

I will let @jaypeecee answer this. But I guess the idea is that if there would be unlimited supply of ammonia available for the plants they will never tap into the nitrate dosed or released from nitrification and thus the nitrate would build up in the tank... I suppose this could happen in a poorly maintained tank (insufficient WCs) containing a small plant mass relative to a high stocking level and insufficient nitrification through bio filtration etc.?

Cheers,
Michael

 

[Maf 2500]

I will let @jaypeecee answer this. But I guess the idea is that if there would be unlimited supply of ammonia available for the plants they will never tap into the nitrate dosed or released from nitrification and thus the nitrate would build up in the tank... I suppose this could happen in a poorly maintained tank (insufficient WCs) containing a very small plant mass relative to a high stocking level and low nitrification through bio filtration etc.?

Cheers,
Michael

Yes, but if significant amounts of ammonia were constantly available in sufficient quantities that the plants could afford to ignore nitrates then all the livestock would be dead or seriously ill?

 

[MichaelJ]

all the livestock would be dead or seriously ill?

Yes, unless I am missing something, that would possibly be the worst case scenario... unless the plants would just be doing a good enough job to perpetually keep the free ammonia (NH3) below the toxic levels (an unlikely long term scenario)... which is also regulated by pH and water temperature btw.

Cheers,
Michael

 

[dw1305]

Hi all,

that plants prefers ammonium and do not consume nitrates when there is enough ammonium in the water.

But I guess the idea is that if there would be unlimited supply of ammonia available for the plants they will never tap into the nitrate dosed or released from nitrification and thus the nitrate would build up in the tank... I suppose this could happen in a poorly maintained tank (insufficient WCs) containing a small plant mass relative to a high stocking level and insufficient nitrification through bio filtration etc.?

Surely the established practice of dosing nitrates into the water column via EI, or other nutrient regimes, and said practice not causing excess nitrate problems proves that aquatic plants uptake nitrates?

Yes, I think that is it. It's the <"continually replenished ribs"> scenario at the all day buffet. I would have just totally discounted it, but I'm guessing it's theoretically possible, but only with <"insane stocking densities">.

One thing I'd say straight away is that you are going to have a lot less ammonia entering microbial nitrification in planted systems and that alone this will greatly reduce nitrate (NO3) production.

There is research from aquaculture which suggests that nitrate accumulation really isn't a problem:
<"Ng, Y & Chan, D, (2021). The role and effectiveness of monoculture and polyculture phytoremediation systems in fish farm wastewater. RSC Advances, 11(23), pp.13853-13866. "> says

......... This study intended to evaluate the roles and treatment profiles of Spirodela polyrhiza (L.) Schleid. and Lemna sp. systems in terms of ammonia, nitrate, nitrite, phosphate (NH3–N, NO3−–N, NO2−–N, PO43−), chemical oxygen demand (COD), turbidity, and total suspended solids (TSS) on fish farm wastewater and to elucidate the rationale behind the removal of the pollutants and the changes in a raceway pond rig. The nitrogen and phosphorus removal in the Spirodela polyrhiza monoculture system outperformed the other configured systems. An 81% reduction in ammonia (to 3.90 mg of NH3-N/L), and sharp declines of up to 75%, 88%, and 71% in TSS, turbidity, and COD levels were recorded within two days, while significant decreases in nitrate, nitrite, and phosphate levels were observed. .......

and this is from <"Paolacci, S., Stejskal, V. & Jansen, M. (2021) "Estimation of the potential of Lemna minor for effluent remediation in integrated multi-trophic aquaculture using newly developed synthetic aquaculture wastewater." Aquacult Int 29, 2101–2118">.

......... The concentration of NO3ֿ-N in the medium decreased slowly over the 4 days of monitoring (Fig. 2b). The concentration of NO3ֿ-N in the SAW reached values as low as 13.5 ± 1.6 mg·l-1 at the highest plant density and after 4 days...........

Because the Paolacci et al. paper used a floating plant (Lesser Duckweed (Lemna minor)) I think you can discount anaerobic denitrification as a source of NO3 removal.

cheers Darrel

 

[jaypeecee]

I don't understand this comment, I hope I am not being thick and missing something obvious. Surely the established practice of dosing nitrates into the water column via EI, or other nutrient regimes, and said practice not causing excess nitrate problems proves that aquatic plants uptake nitrates?

Hi @Maf 2500

Please don't shoot the messenger! I'm simply communicating information that anyone can read in the documents that have been cited in the latter posts of this thread. The $64,000 question here primarily concerns preferential uptake of ammonium over nitrate. But, when you say "said practice not causing excess nitrate problems", some aquarists choose not to measure nitrate. That being the case, how would they know if nitrate was excessive, whatever we decide that means? We cannot equate excess nitrate with algae growth, for example - it's just not that simple.

JPC

 

[dw1305]

Hi all,

The $64,000 question here primarily concerns preferential uptake of ammonium over nitrate. But, when you say "said practice not causing excess nitrate problems", some aquarists choose not to measure nitrate.

I have measured nitrate levels in the tank, we have <"ion selective electrodes"> etc. If nitrate testing was quick and easy (like using a conductivity meter) I would recommend people tested for nitrate, if they felt they needed to.

Usually I just measure conductivity. If I only have 120 microS conductivity, even if every one of those conducting ions was a NO3- ion? There still wouldn't be very many of them

I really just don't understand where this is going, other than around in circles. We <"know plants have">:

• A <"large requirement for fixed nitrogen"> and
• can take it up in all three of its forms (NH3/NH4+, NO2- & NO3-) and that
• most aquascapers supply extra fixed nitrogen exclusively as nitrate (NO3-), the anion from the dissolution of potassium nitrate (KNO3) and that
• fixed nitrogen is a scarce resource in natural environments and that
• plants have evolved "luxury uptake" as a means of coping with nitrogen "boom and bust".

Assuming we have the <"other nutrients required for plant growth"> why would NO3 accumulate in a planted tank?

If plants are preferentially taking up <"Total Ammoniacal Nitrogen"> (TAN)? That just means less TAN enters microbial ammonia oxidation and less nitrate is ever produced. It is negative feedback loop. The only way nitrate could accumulate would be if we continually added fixed nitrogen and never harvested any of the plant growth. If we let the plants senesce ("re-enter the nitrogen cycle") within the tank eventually NO3 would accumulate, but the vast majority of it will always be in the plant tissue.

.......... That being the case, how would they know if nitrate was excessive, whatever we decide that means? We cannot equate excess nitrate with algae growth .....

No, but we can directly <"relate fixed nitrogen availability with leaf colour and size in a non-CO2 limited plant">. It may be <"inferential"> but if it is a good enough technique to <"feed half the World's population?"> I'd regard as <"fairly robust">.

cheers Darrel

 

[John q]

Just like to say excellent post above by darrel.

The $64,000 question here primarily concerns preferential uptake of ammonium over nitrate

I don't think there's much debate as to whether aquatic plants will uptake ammonium in preference to nitrate, the real $64,000 question is whether or not they grow any better when exclusively fed NH4, Diana walstad also concedes this.

There's lots of threads on ukaps, barr report and planted tank that have asked this question, and there are a number of people that have ran experiments, including yourself, to try and find the answer to this. I don't believe anybody to date has come up with any compelling evidence that suggests dosing with ammonium alone produces better results than dosing with nitrates.

Back to the original question on nitrate accumulation. I used to test my water quite frequently and was satisfied my results were consistent.
Before I started dosing nitrates the ppm levels would consistently hover around 5~10 ppm on a weekly basis. I started dosing 10 ppm of nitrate pw and the weekly readings increased to 15~20 ppm.
It quickly became apparent that whatever waste my fish were producing was sustaining the level of plants I had at that time and any excess nitrates would be removed at the weekly water change.

That's the main reason I stopped testing the water, it became obvious to me what my readings would be before I took them.

Why am I saying this... Well, if you could add a known amount of nh4 that would exactly satisfy the plants needs(including luxury uptake) then any fish waste, assuming we had a filter, would be turned into nitrates, if this excess wasn't removed, at some point "insert arbitrary figure here" the nitrate levels would become toxic.

I always like your questions @jaypeecee they certainly arouse conversations, but I must agree with darrel when he asks where you plan to take this inquisitive thought you have.

 

[jaypeecee]

I always like your questions @jaypeecee they certainly arouse conversations, but I must agree with darrel when he asks where you plan to take this inquisitive thought you have.

Hi @John q

Thanks for the feedback.

I don't think there's much debate as to whether aquatic plants will uptake ammonium in preference to nitrate...

And if aquatic plants consume all available ammonium, then the nitrifying bacteria (and/or Archaea) are deprived of an ammonium source. I'm unclear as to the full implications of this.

...the real $64,000 question is whether or not they grow any better when exclusively fed NH4, Diana walstad also concedes this.

This is something that I had not considered. Does Diana Walstad cover this in her book, Ecology of the Planted Aquarium?

Back to the original question on nitrate accumulation. I used to test my water quite frequently and was satisfied my results were consistent.

That is also my preferred approach. But if the bio filter is not cleaned as part of regular water changes, then it can become a nitrate factory. And if regular nitrate tests are not conducted, then what? So, now, the bio filter is potentially no longer an asset but a liability. For this reason, I would prefer to let my plants be the sole aquarium water purifier. And this hopefully explains my curiosity and the reason for pursuing this topic.

JPC

 

[Jaseon]

You know i cant help but think we sometimes over think this stuff.

 

[sparkyweasel]

And if aquatic plants consume all available ammonium, then the nitrifying bacteria (and/or Archaea) are deprived of an ammonium source. I'm unclear as to the full implications of this.

I suspect that the bacteria (etc) would consume some of the ammonia before the plants could take all of it.

 

[Jaseon]

What about plant only tanks? Ive heard of people having heavily planted tanks with no filtration.

 

[MichaelJ]

Hi @jaypeecee ,

And if aquatic plants consume all available ammonium, then the nitrifying bacteria (and/or Archaea) are deprived of an ammonium source. I'm unclear as to the full implications of this.

I find it rather unlikely that the plants could mob up all the ammonia and leave nothing for bio filtration - it might be that the levels are low and the bacteria colony would just be smaller - the bio filtration would still work in your favor as a safety belt.

That is also my preferred approach. But if the bio filter is not cleaned as part of regular water changes, then it can become a nitrate factory. And if regular nitrate tests are not conducted, then what?

Agreed. Regular filter cleaning is key... How do you measure NO3 level consistently btw.? My NO3 readings using the API test kit could be anywhere from 40 to 160ppm.... realistically its probably around 30ppm.

So, now, the bio filter is potentially no longer an asset but a liability.

How so? if the bacteria colony is just reduced due to the competition with plants why would that make it a liability.

For this reason, I would prefer to let my plants be the sole aquarium water purifier.

I agree. That is what I prefer as well. A massive plant to livestock ratio. I am starting to think of my filtration as mostly mechanical filtration and a source of flow and circulation and much less about the bio filtration given my plant mass, but I do not doubt for a second that some is happening and that it is beneficial.

Cheers,
Michael