# Phosphate in tapwater



## James53 (10 Oct 2021)

Hi all. I have a two ish week easy plants tank using liquid co2 and weekly tnc complete. My ammonia is nearly zero and nitrate coming good. Kh was slightly low so dosed slightly  that. Phosphate is about 1 ppm on salifert test. LFS said this is high and should be about 0.25. tested tap water and that's about 1 also. Should I use NT labs anti phosphate (or similar?) Get this down from now on? Thanks


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## John q (10 Oct 2021)

Hi James, I wouldn't take much notice of the advice given out by local fish stores, especially concerning planted tanks. At best they are ill informed, at worst they are trying to sell you more unnecessary products.

Plants need phosphate to survive, trying to remove it will cause deficiencies in the plants.
I add phosphate to my tanks and the levels sit around 3ppm, others dose higher rates than this and no harm comes to the fish. Also worth mentioning that phosphates at these levels DO NOT CAUSE ALGAE.

This thread might be worth a read.
Post in thread 'EI Dosing and Phosphate Level' EI Dosing and Phosphate Level


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## erwin123 (10 Oct 2021)

TNC Complete contains phosphate.... you shouldn't be dosing ferts and simultaneously using 'NT labs anti phosphate'?


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## dw1305 (10 Oct 2021)

Hi all, 
@James53 I agree with the other posters. 


James53 said:


> LFS said this is high and should be about 0.25. tested tap water and that's about 1 also. Should I use NT labs anti phosphate (or similar?) Get this down from now on? Thanks


I'll give them the benefit of the doubt and assume that they honestly don't know what <"they are talking about"> in this case. They might be really good with fish, but they don't know anything about planted tanks. The other option is that they know the product they've recommended is pointless, but they have <"tried to sell it to you anyway">.   

To cut to the chase all you need to maintain water quality is <"plenty of oxygen"> and a <"lot of plants"> in growth, everything else is <"just froth">. 

To get back to the subject:

Phosphate in natural water is a marker for eutrophication, and the environment (both aquatic and terrestrial) is <"awash with excess levels of phosphate (PO4---)">, <"but plants (and particularly floating ones)"> are very effective at reducing phosphorus (P) levels.  
Phosphorus is on the of the <"three macronutrients">, (N : P : K) along with nitrogen (N) and potassium (K)
All UK tap water has <"orthophosphate added to it">, to ensure that lead (Pb) levels stay below 50 ppb.  
cheers Darrel


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## dw1305 (10 Oct 2021)

Hi all, 


James53 said:


> Kh was slightly low so dosed slightly that.


Where do you live in Pembrokeshire? If you live <"south of the Landsker Line"> you are likely to have <"hard water (from the limestone)"> and further N. softer water from the Preseli etc. 

cheers Darrel


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## James53 (10 Oct 2021)

Haverfordwest


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## dw1305 (10 Oct 2021)

Hi all,





James53 said:


> Haverfordwest


Could be either, geology is Old Red Sandstone.  You should be able to get figures from the Welsh Water link.

Cheers Darrel


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## sparkyweasel (10 Oct 2021)

dw1305 said:


> They might be really good with fish, but they don't know anything about planted tanks.


If they were _really _good with fish, they would know that the best home for most pet fish is a planted tank.


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## Andy Pierce (10 Oct 2021)

James53 said:


> Kh was slightly low so dosed slightly that.


KH was slightly low for what purpose?  Unless you are trying to do something that requires a specific KH, e.g. breeding shrimp, I wouldn't worry about it.


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## John q (10 Oct 2021)

Mate your kh gh ph is fine, Pembrokeshire water is fine. That bloke that sells baterd fish down the road is fine. Over reading information into planted tanks isn't fine. 😁


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## MichaelJ (10 Oct 2021)

dw1305 said:


> I'll give them the benefit of the doubt and assume that they honestly don't know what <"they are talking about"> in this case. They might be really good with fish, but they don't know anything about planted tanks.



It's surely not only the average LFS that's off with regards to Phosphate. This is what the instruction reads for a very popular Phosphate test kit:
_"Ideally, the phosphate level should be zero in saltwater aquariums and freshwater aquariums or ponds, including those containing live plants."_

I intentionally keep my Phosphate levels at 10 ppm with my weekly dosing and been doing so for a long time now and have been able to completely eradicate GSA on slow growers such as Anubias. Fish, shrimps and plants are completely fine with this. Large unintentional build-up of phosphate (and nitrate for that matter) on the other hand usually goes hand in hand with large build-ups of organic waste due to poor maintenance. 

Cheers,
Michael


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## dw1305 (11 Oct 2021)

Hi all,


MichaelJ said:


> "Ideally, the phosphate level should be zero in saltwater aquariums and freshwater aquariums or ponds, including those containing live plants."


Agreed it is a <"nonsensical statement">.

If you were interested in testing, phosphorus (P) (as orthophosphate (PO4---)) is actually one of <"the easier ions to test for">, this is because most phosphate compounds <"are insoluble"> and a <"lot of them are coloured">.


MichaelJ said:


> I intentionally keep my Phosphate levels at 10 ppm with my weekly dosing and been doing so for a long time now and have been able to completely eradicate GSA on slow growers such as Anubias.


We don't know why this works.

My guess would be that that the suppression of "Green Spot Algae" (GSA) is actually an iron (Fe) effect and that <"the excess of PO4--- mops up any Fe+++ ions"> before they can diffuse into the algal cells. Algae don't have any <"internal "plumbing"> and can only make use of ions that diffuse in through the cell walls.

I don't tend to have much GSA (again I don't really know why), but possibly because I have a lot of <"floating plants">, soft water and I run the tanks nutrient depleted.

cheers Darrel


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## Andy Pierce (11 Oct 2021)

GSA is a mysterious beast.  I'm happy with my current GSA status giving the aquarium walls if needed a light monthly scraping and the plants doing well.  I'm convinced through direct experimentation that too much light causes GSA, but much less convinced that anything else, including phophate levels, has any material impact on GSA either positively or negatively.  I have very hard water (Cambridgeshire tap), run at full EI dosing rather than nutrient depleted, and haven't got any floating plants, so quite a contrast to @dw1305.  There could very well be multiple paths to success here.


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## dw1305 (11 Oct 2021)

Hi all,


Andy Pierce said:


> There could very well be multiple paths to success here


I'm sure there are.

I always think it is a <"_shades of grey_"> world in <"aquarium keeping">.

cheers Darrel


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## MichaelJ (11 Oct 2021)

dw1305 said:


> My guess would be that that the suppression of "Green Spot Algae" (GSA) is actually an iron (Fe) effect and that <"the excess of PO4--- mops up any Fe+++ ions"> before they can diffuse into the algal cells. Algae don't have any <"internal "plumbing"> and can only make use of ions that diffuse in through the cell walls.


Very interesting. 

Another thing about phosphate is how it affects _real_ ecosystems with respect to algae growth. Around here in Minnesota the local watershed managements are tackling this by building what essentially are very large rain gardens to capture the phosphorus run-off from storm-drains, household gardens etc.  before it ends up in the lakes and cause algae problems.

Cheers,
Michael


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## dw1305 (11 Oct 2021)

Hi all,


MichaelJ said:


> Around here in Minnesota the local watershed management are tackling this by building what essentially are very large rain gardens to capture the phosphorus run-off from storm-drains, household garden etc. before it ends up in the lakes and cause algae problems.


Yes, we like these, they are <"Constructed Wetlands"> and they were one of the things that <"made me think a lot more carefully"> about aquarium filtration. I worked with <"Ana Castro-Castellon"> for a while.

cheers Darrel


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## plantnoobdude (11 Oct 2021)

thought i'd share my experience. 
a few weeks ago I was experiencing horrible GSA. every week my ludwigia's lower leaves would be covered, and the tanks glass would be green and fairly hard to see through, if i don't clean it 2 or 3 times a week.
i was dosing standard EI
30, 3, 20ppm No3, Po4 and K. and 0.6ppm Fe.
i upped my po4 dosing to 5ppm/week, and this is the glass 6 days after last water change.


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## MichaelJ (11 Oct 2021)

Hi @plantnoobdude Pretty impressive!!



plantnoobdude said:


> and the tanks glass would be green and fairly hard to see through, if i don't clean it 2 or 3 times a week.


Thats another thing. I very, very rarely have to clean my glass or hardscape/equipment surfaces etc.... Granted, I do believe its a combination that makes it work; an abundance of NPK, low light intensity, proper filtration and maintenance (WC's), not just high PO4 dosing...  Of course,  there is never such thing as zero algae, it's just getting to the point, and keeping it there, where algae is never a nuisance that catches your eyes or is impairing plant growth or health.   Thinking of our challenges in this hobby holistically and more in _shades of gray,_ as @dw1305 puts it, seems like a good common sense approach to me.

Cheers,
Michael


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## dw1305 (12 Oct 2021)

Hi all,


MichaelJ said:


> Thinking of our challenges in this hobby holistically and more in _shades of gray,_ as @dw1305 puts it, seems like a good common sense approach to me.


It was really <"Diana Walstad's book"> that started me down the <"_shades of grey route_">. It isn't a very snappy title ("_Ecology of the Planted Aquarium: A Practical Manual and Scientific Treatise for the Home Aquarist_"), but as a book it does what it says it does. Ecology is all shades of grey.

Personally it isn't a very exciting, or innovative approach, but when I'm making changes I use a combination of <"experience, probability and risk management">.  


Tim Harrison said:


> In short if your plants are still growing well and you've got no algae go with it - if it ain't broken don't fix it...


In terms of making changes, I tend to go with <"_if it isn't broke don't fix it_"> as well.


dw1305 said:


> I'd be the first to admit I'm a pretty shoddy fish keeper and because of that I like risk management. It isn't a very exciting approach, but you isolate all the single points of failure and then you try and build in extra capacity and negative feed-back loops.



cheers Darrel


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## Luvlyjub (4 Jan 2022)

Coming in late to this thread as I am trying to research phosphate levels in relation to algae. I have recently successfully treated one of my tanks that had an algae issue but the top layer of coral substrate and lower glass will still need regular cleaning that I assume to be GSA. My issue may have been new tank syndrome following a replant and rescape a few months back but like most we tend to look for reasons and water chemistry is one topic that seems to divide opinion.

Now I recall watching a very informative video about all the major algae types with identification and treatment advice and the last point was GSA and phosphate levels. As mentioned too high or too low PO4 could be a cause of GSA and so rightly or wrongly I purchased a test kit. I know many dismiss the accuracy of test kits but I find JBL more reliable provided you follow the instructions and apply some common sense. Anyway my result was immediately dark blue and the scale of JBL only goes to 1.8ppm and my assumption was that this was high and possibly an issue? However, reading this thread I am now not so sure - to point out my tank is not heavily planted and my nitrate levels were fine and I had just done a 50% water change the day before. So I checked my tap water and again same result that is above 1.8ppm, subject to your view on test kit results.

At the moment my tank looks fine and if all I need to do is a scrape and brush once a week to keep on top of some algae then fine as that's part of the hobby with maintenance. But now I have an awareness of what is perceived by the information out there as high phosphate in my tap water should I really be concerned? Is this (along with all the other factors that can cause algae) one of the root problems that I should consider treating to lower the phosphate level from source?

Michael - I note your post with interest that you maintain high phosphate but does this not deplete over the period with uptake from the plants?

Would I be right to assume that an optimum PO4 level (if there is one) is relative to the density of planting and type of ferts you are using. And then if a higher PO4 does inhibit GSA does it not then have a potential negative impact with other types of algae or is this only in combination with N?


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## jaypeecee (4 Jan 2022)

Luvlyjub said:


> I know many dismiss the accuracy of test kits but I find JBL more reliable provided you follow the instructions and apply some common sense. Anyway my result was immediately dark blue and the scale of JBL only goes to 1.8ppm and my assumption was that this was high and possibly an issue?


Hi @Luvlyjub 

I use the JBL PO4 (sensitive) test kit and it serves me well. As you have noted, the maximum reading that it can handle is 1.8 ppm. In order to measure in excess of this figure, it is necessary to dilute the tank water sample or tap water sample using RO/DI, low conductivity rainwater or distilled water. So, if you were to dilute the tank or tap water sample with an equal amount of RO/distilled water, that would be a factor of two dilution. From this diluted sample, you would still use 10ml in order to carry out the test. This principle can be extended to increase the upper PO4 limit. Now, let's say that this time around, the diluted sample matches the 1.2 ppm colour patch. You'd simply multiply this by 2, which would give you 1.2 x 2 = 2.4 ppm.

I hope that's clear.

Please let us know the outcome and then we can discuss this further.

JPC


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## Luvlyjub (4 Jan 2022)

jaypeecee said:


> So, if you were to dilute the tank or tap water sample with an equal amount of RO/distilled water, that would be a factor of two dilution


An excellent idea. I will do this later this week with RO/DI water and report result.


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## MichaelJ (4 Jan 2022)

Luvlyjub said:


> Michael - I note your post with interest that you maintain high phosphate but does this not deplete over the period with uptake from the plants?


Hi @Luvlyjub Yes, I have kept dosing 10ppm with my weekly WC for a long time.  I mix in the KH2PO4 (along with my other salts) targeting my 40% WC water with 10ppm of PO4 to to maintain that level in the tank minus the uptake. My tanks are densely planted, but low-energy, so I guess the uptake is fairly low - perhaps a net change of -1 ppm/wk.  So, my guesstimated equilibrium level is probably around 8.5 ppm. (I don't have much buildup from waste...).



Luvlyjub said:


> Would I be right to assume that an optimum PO4 level (if there is one) is relative to the density of planting and type of ferts you are using.


I think plant mass always has to be taken into consideration.



Luvlyjub said:


> And then if a higher PO4 does inhibit GSA does it not then have a potential negative impact with other types of algae or is this only in combination with N?


I haven't noticed ANY negative impact from the high PO4 (or high N/NO3, K or Fe dosing for that matter)... I have excellent plant health, zero algae to speak of (I rarely even have to clean the inside of my front glass)  So my overall maintenance routine with all it entails,  have definitely been working out long term in both my tanks.

Now, my two tanks are very similar in terms of stocking level and especially plant mass and in light of recent long-running discussions about fertilization I am currently contemplating slowly putting one of my tanks on a "diet" and apply some of the lean-dosing ideas that some fertilizer experts seems to have good success with. My agenda is to see if I can make a dent in my TDS for the benefit of my livestock while maintaining the same level of plant health. Its probably going to be some sort of hybrid approach as I need to maintain certain levels for my shrimps (such as Ca and Mg ppm's).

Cheers,
Michael


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## Jaseon (4 Jan 2022)

All bacteria need a little bit of phosphate?


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## jaypeecee (4 Jan 2022)

Jaseon said:


> All bacteria need a little bit of phosphate?


Hi @Jaseon 

Yes, phosphorus (as phosphate) is very important to bacteria. But, it's important to all living things as ATP* is fundamental to life (as we know it).

* Adenosine Triphosphate

JPC


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## Luvlyjub (5 Jan 2022)

jaypeecee said:


> Please let us know the outcome and then we can discuss this further.


OK so with JBL test diluted tap water with DI 50% and then 25% I come up with a consistent 2.4ppm PO4.

The questions are -

Should I just accept this level in my tap water and use in my aquariums without trying to reduce?
Is such level in the goldilocks zone to inhibit GSA (if proven) or is it too high and a propensity to cause other potential algae issues?
Is the concern with PO4 levels dependent on level of plant mass and type of ferts used?

Michael - I note that your method is to maintain a high PO4 in excess of the plants requirements and from your experience have little algae issues.

I suppose each circumstance is different as algae has a number of influencers and I guess I am trying to point the finger at a potential culprit with the phosphate level. As I have been oblivious to the phosphate in my tap water and therefore aquariums for 20 years I wonder if I really need to be concerned but welcome advice from others.


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## Jaseon (5 Jan 2022)

jaypeecee said:


> Hi @Jaseon
> 
> Yes, phosphorus (as phosphate) is very important to bacteria. But, it's important to all living things as ATP* is fundamental to life (as we know it).
> 
> ...


I was going off what Dr Tim mentioned how _Heterotrophic_ bacteria was using up the phosphate robbing the nitrifiers.


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## arcturus (5 Jan 2022)

Luvlyjub said:


> Should I just accept this level in my tap water and use in my aquariums without trying to reduce?
> Is such level in the goldilocks zone to inhibit GSA (if proven) or is it too high and a propensity to cause other potential algae issues?
> Is the concern with PO4 levels dependent on level of plant mass and type of ferts used?


1. There is no "proven" way to inhibit GSA; not even the factors that limit or stimulate GSA (and most other algae) are well understood.

2. You should not be concerned with "excess" macronutrient levels, including PO4, but with nutrient deficiency (and availability and distribution of CO2).

3. <Some studies (see snippet below)> link the N : P ratio (and not their absolute concentration) to algae limitation and stimulation. For example, Barr's EI proposes a 10:1 N : P ratio. <Other methods, such as the Redfield>suggest 16:1.


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## jaypeecee (5 Jan 2022)

Hi @arcturus 

You may find the following to be of relevance:






						Cyanobacteria Identification - At Last!
					

Hi again!  Along with the UV-C sterilizer, it will still be necessary to use Easy-Life Blue Exit. May I also request that UKAPS members keep this within UKAPS' four walls? I don't want someone else nabbing the idea and claiming ownership of it. I don't seek to benefit from it other than to...



					www.ukaps.org
				




JPC


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## arcturus (5 Jan 2022)

jaypeecee said:


> Hi @arcturus
> 
> You may find the following to be of relevance:
> 
> ...



Thanks! There are many open questions. It is hard to correlate the ratios found in natural environments with their actual impact. The worse part of it is that many correlations are scientifically weak since they rely in simple observations with few or no controlled variables. And it is even harder to extrapolate the correlations to planted aquariums...


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## ceg4048 (8 Jan 2022)

Luvlyjub said:


> Should I just accept this level in my tap water and use in my aquariums without trying to reduce?


Yes.


Luvlyjub said:


> Is such level in the goldilocks zone to inhibit GSA (if proven) or is it too high and a propensity to cause other potential algae issues?


No. Add as much PO4 as you like. There are no repercussions of high PO4, only of low PO4.
There is no "Goldilocks Zone". Required nutrient uptake is a function of light intensity, temperature and nutrient availability. It therefore changes as these variables change.


Luvlyjub said:


> I wonder if I really need to be concerned but welcome advice from others.


Fretting about high PO4 levels in a freshwater planted tank is fruitless.


arcturus said:


> 3. <Some studies (see snippet below)> link the N : P ratio (and not their absolute concentration) to algae limitation and stimulation. For example, Barr's EI proposes a 10:1 N : P ratio. <Other methods, such as the Redfield>suggest 16:1.


There is no relationship in our tanks of N to P ratios with algal blooms. The related blooms occur as a result of any limitation of N or P. Barr does not suggest a magical ratio in order to deter algae. His ratio was determined by the simple arithmetic based on the numbers used when the values of each were determined to be unlimited.

Cheers,


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## hypnogogia (8 Jan 2022)

@ceg4048, I hear what you say about the ratios, but would it be normal for nitrates to be higher than PO4?


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## jaypeecee (8 Jan 2022)

arcturus said:


> Thanks! There are many open questions. It is hard to correlate the ratios found in natural environments with their actual impact. The worse part of it is that many correlations are scientifically weak since they rely in simple observations with few or no controlled variables. And it is even harder to extrapolate the correlations to planted aquariums...


Hi @arcturus

Scientific information is plentiful for those who go looking for it. But, it's not everyone's idea of fun. Determined, as I have been, to obtain facts, I now have a small library of scientific papers dealing with virtually all subjects of interest (to me) in the field of freshwater aquatics. As you can imagine, little scientific work has been done in the aquatics hobby per se. But, there are notable exceptions - such as the pioneering work of Dr Tim Hovanec relating to nitrifying bacteria.

If the science behind our hobby is of interest to you, do you have a copy of Diana Walstad's _Ecology of the Planted Aquarium_? This book has taught me a great deal about planted aquaria. In this book, she also makes numerous references to the seminal work by Robert G Wetzel - _Limnology_ (3rd Edition).

JPC


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## arcturus (10 Jan 2022)

ceg4048 said:


> There is no relationship in our tanks of N to P ratios with algal blooms. The related blooms occur as a result of any limitation of N or P. Barr does not suggest a magical ratio in order to deter algae.  His ratio was determined by the simple arithmetic based on the numbers used when the values of each were determined to be unlimited.


I am aware of reports of successful planted tank keepers that seem to show that these ratios are not relevant. But there are other successful planted tank keepers that report otherwise.  Are any conclusive (scientific) studies that demonstrate that such ratios do not correlate to algal blooms in planted tanks? Can we dismiss N : P : K ratios, and other ratios such as Ca : Mg? 

The fact is that there are <studies> <analyzing> <the role of> of the N : P, N : K ratio and other ratios and limitation factors in natural ecosystems. There are also studies suggesting the importance of <the interplay between multiple factors>, which would be unsurprising since we are dealing with a dynamic <complex system>. If there were definitive answers to these questions, then we wouldn't have so many different approaches to planted tank keeping but a general framework that would apply to a majority of setups, which is not the case.


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## dw1305 (10 Jan 2022)

Hi all, 


arcturus said:


> If there were definitive answers to these questions, then we wouldn't have so many different approaches to planted tank keeping but a general framework that would apply to a majority of setups, which is not the case.


<"Same for me really">, too many <"unknown unknowns"> to quantify exactly what is happening. I think I know (understand?) how you can keep <"low tech tanks fairly stable">, but I don't have any empirical evidence. 

cheers Darrel


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## jaypeecee (10 Jan 2022)

Hi Everyone,

If I have time today, I will try to pull together some scientific studies and hobbyists' observations/data that are very relevant to the topic(s) being discussed here.

JPC


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## Ria95 (10 Jan 2022)

arcturus said:


> 3. <Some studies (see snippet below)> link the N : P ratio (and not their absolute concentration) to algae limitation and stimulation. For example, Barr's EI proposes a 10:1 N : P ratio. <Other methods, such as the Redfield>suggest 16:1.


It's often useful to play a though experiment. If ratios of N : P :K are an important aspect leading to algae growth in aquariums then it will be easy to induce (and stop ?) algae blooms. The 'faulty ratios'  will also be common across many tanks experiencing algae blooms and many concentrations (more on this later). We have seen such strong interdependence situations with the light-CO2-nutrients triangle.
If however  the rations of N : P :Kare not an important aspect that determines algae growth in the aquarium there will be aquariums with algae and aquariums without algae at the same ratios, aquariums without algae blooms at a wide range of ratios. The experiments to induce the algae blooms would be non-repeatable or will not apply across a wide range of light, CO2 levels and concentrations. In practice other aspects will fix the algae bloom then coming to a "N : P :K ratio of algae limitation". In other words N : P :K would be just one of the many small factors that may or may not influence a little bit if there is a bloom or not in our aquariums.

TLDR: Makes sense, if N : P :K plays a very important aspect of algae blooms it will be very common across many other variables and it will be very easy to induce algae with it.


arcturus said:


> I am aware of reports of successful planted tank keepers that seem to show that these ratios are not relevant. But there are other successful planted tank keepers that report otherwise.  Are any conclusive (scientific) studies that demonstrate that such ratios do not correlate to algal blooms in planted tanks? Can we dismiss N : P : K ratios, and other ratios such as Ca : Mg?
> 
> The fact is that there are <studies> <analyzing> <the role of> of the N : P, N : K ratio and other ratios and limitation factors in natural ecosystems. There are also studies suggesting the importance of <the interplay between multiple factors>, which would be unsurprising since we are dealing with a dynamic <complex system>. If there were definitive answers to these questions, then we wouldn't have so many different approaches to planted tank keeping but a general framework that would apply to a majority of setups, which is not the case.


If N : P ratios are relevant over concentrations then the same effect on algae amount and type will occur at

10 mg/L N ,1 mg/L P; N : P 10:1
0,01 mg/L N, 0,001 mg/L P ; N : P 10:1
-100 mg/L N, 10 mg/L P; N : P 10:1
If you don't get the same effect it may be more worth to look at concentrations than ratios.
The same rationale applies to effects of ratios on plant quality and growth rate. Few proponents of various golden ratios bother to test  the same ratio across 2 logs of concentration to check if indeed it is the ratio that makes the effect.  Quite the contrary, as more data comes in the same proponents of the golden ratio start saying ' it works across quite a large range of ratios', 'you don't have to be that specific' and add some footnotes ' as long as X is kept above this value'. The golden ratio remains as optimal somehow, just through inertia.



> For example, Barr's EI proposes a 10:1 N : P ratio.


As far as I have seen the Estimative Index never recommended ratios, even less 10:1 N : P. In the original article  the recommended ranges for EI are:
"
CO2 range 25-35ppm
NO3 range 5-30ppm
K+ range 10-30ppm
PO4 range 1.0-3.0 ppm
Fe 0.2-0.5ppm or higher (?)
GH range 3 degrees ~ 50ppm or higher
"
If you really want to force ratios out them you have between 3.5:1 to 6.9:1 N : P--not 10:1. If you want to use the figures from Rotala Butterfly | Planted Aquarium Nutrient Dosing Calculator for EI you still end up with a ratio of 4:1 N : P by mass, very far from the referenced 10:1. I have to think part of the high PO4 dosage is to counteract the phosphate fearmongering at the time EI was published, the nutrient fearmongering seems to be blooming again.


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## jaypeecee (10 Jan 2022)

ceg4048 said:


> There is no relationship in our tanks of N to P ratios with algal blooms. The related blooms occur as a result of any limitation of N or P. Barr does not suggest a magical ratio in order to deter algae. His ratio was determined by the simple arithmetic based on the numbers used when the values of each were determined to be unlimited.



Hi @ceg4048

Please take a look at the following link  - Tom Barr's entry. Then scroll down to Roger Miller's entry. I suspect the figures being discussed had their origin in the Redfield Ratio (RR). My understanding is that the RR is now not considered to be applicable to the aquarium ecosystem. At this point, it may be best to go to _The Krib_ discussion:



			Phosphorus
		


I'm sure you will have read this disscussion before but other UKAPS members may be new to it. OK, I now have a question for you. And that is - when you say "There is no relationship in our tanks of N to P ratios with algal blooms. The related blooms occur as a result of any limitation of N or P". Are you referring to all forms of N and P that exist in our tanks?

JPC


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## arcturus (10 Jan 2022)

Ria95 said:


> (...) TLDR: Makes sense, if N : P :K plays a very important aspect of algae blooms it will be very common across many other variables and it will be very easy to induce algae with it.


Are you saying that by keeping light and CO2 constant you cannot trigger algal blooms through the variation of NPK ratios and concentrations?



Ria95 said:


> (...) The same rationale applies to effects of ratios on plant quality and growth rate. Few proponents of various golden ratios bother to test  the same ratio across 2 logs of concentration to check if indeed it is the ratio that makes the effect.  Quite the contrary, as more data comes in the same proponents of the golden ratio start saying ' it works across quite a large range of ratios', 'you don't have to be that specific' and add some footnotes ' as long as X is kept above this value'. The golden ratio remains as optimal somehow, just through inertia.


Studies in natural ecosystems (such as the ones I linked), do not separate the analysis of concentrations from the ratios. They are two sides of the same coin. Algal blooms are correlated to nutrient ratio at a given concentration. In short, it is not only about the ratio, but ratio at a given ppm. Whether these observations in natural ecosystems apply to planted tanks or not is another question.



Ria95 said:


> (...) If you really want to force ratios out them you have between 3.5:1 to 6.9:1 N : P--not 10:1. If you want to use the figures from Rotala Butterfly | Planted Aquarium Nutrient Dosing Calculator for EI you still end up with a ratio of 4:1 N : P by mass, very far from the referenced 10:1.


The EI target is 30 ppm NO3 to 3 ppm PO4. That is 10 : 1. That gives roughly 4.5 : 1 of N : P. So, we are talking about the same thing using different units.


Ria95 said:


> I have to think part of the high PO4 dosage is to counteract the phosphate fearmongering at the time EI was published, the nutrient fearmongering seems to be blooming again.


This is not about nutrient fearmongering but about scientific evidence. Either there is validated data sustaining that the ratios and their underlying concentrations are irrelevant on a planted tank or there is not. Otherwise, you cannot make the false inference that EI "works" (which is far from being a universal fact) because ratios play no role. We should not worry about about nutrient fearmongering, but about promoting the potential virtues of a method while dismissing open questions without any scientific basis.


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## Ria95 (10 Jan 2022)

arcturus said:


> The EI target is 30 ppm NO3 to 3 ppm PO4. That is 10 : 1. That gives roughly 4.5 : 1 of N : P. So, we are talking about the same thing using different units.


I'm using mg/L or ppm. I will make no assumption about you, but the two below are still saying different things with all the units I'm aware of.


arcturus said:


> For example, Barr's EI proposes a 10:1 N : P ratio. <Other methods, such as the Redfield>suggest 16:1.





arcturus said:


> The EI target is 30 ppm NO3 to 3 ppm PO4. That is 10 : 1.


Worth mentioning that the Redfield 16:1 N : P  is a molar ratio? Which highlights another issue with ratios, doesn't it? If you want to make it more comparable it's closer to 7.2 :1 N : P  by mass. If you want to support the hypothesis about ratios you have to pay attention to these things.



arcturus said:


> Are you saying that by keeping light and CO2 constant you cannot trigger algal blooms through the variation of NPK ratios and concentrations?


With the quoted text?, no. In general? I can trigger algae blooms by low concentrations of nutrients leading to plant health issues and lack of growth which  gives the algae an advantage. The nutrient ratios are all over the place during the week but the tanks seems to not experience algae blooms. Thankful for that  . Keeping algae separated by the side is pretty easy in many nutrient concentrations. They are quite hardy.


arcturus said:


> Either there is validated data sustaining that the ratios and their underlying concentrations


So if I say N:Fe 100:1, I'm curious what is the underlying concentration ? Really am because I  cannot make sense of it. 
If I say 10 mg/L NO3-N  and 0.1 mg/L Fe I am a lot clearer. So what is the advantage of ratios if you cannot scale them up or down but still depend on concentrations?



arcturus said:


> This is not about nutrient fearmongering but about scientific evidence. Either there is validated data sustaining that the ratios and their underlying concentrations are irrelevant on a planted tank or there is not. Otherwise, you cannot make the false inference that EI "works" (which is far from being a universal fact) because ratios play no role. We should not worry about about nutrient fearmongering, but about promoting the potential virtues of a method while dismissing open questions without any scientific basis.


I think it quite is. It can be approached from a non-biased, non-fearmongering way and I look forward to that, i.e. "I tried this and this is what i got" instead of starting with "what if algae" "it might hurt us" " we need to".  It may be only me, but ceg's post reads a lot more free.


ceg4048 said:


> No. Add as much PO4 as you like. There are no repercussions of high PO4, only of low PO4.
> There is no "Goldilocks Zone". Required nutrient uptake is a function of light intensity, temperature and nutrient availability. It therefore changes as these variables change.
> Fretting about high PO4 levels in a freshwater planted tank is fruitless.



The 2 papers you referenced and I can access are about cyanobacteria, one quite species specific. I am not aware of any way it can be generalized from cyanobacteria to the many types of algae we experience in aquariums. Maybe you or someone else does. 

Regardless i have suggested quite straightforward ways to support the hypothesis and form the start of a scientific basis with a series of tests where you can show how important N: P :K is. Others have tried here and there  but they still end saying the things i quoted. Plants and algae are adaptable like that, few things break if you go from 4:1 to 3:1 especially when you are speaking about water concentration. Hypotheses abound,  rather looking forward to the data.  I have referenced the EI source as that is the source of the correct proposal/ratios for EI. Sorry if that offended you but thanks for making the core of your focus clear.


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## MichaelJ (10 Jan 2022)

It would be great if someone could explain in layman's terms what the crux of the matter is with fertilizer ratios pertaining to our planted aquariums? and what are the postulates either way?  I don't know much about the biological reasoning behind NPK ratios for aquatic plant keeping. For a long time experts around here have been saying that plants don't really care about ratios... that is not to say that you can't lure out some marginal benefits from dosing at certain NPK ratios relative to concentrations, for instance to promote increased algae growth in a laboratory test or promote or suppress algae in radically different environments such as lakes or rivers, but it certainly doesn't seem critically important for a successful planted aquarium.  For what it's worth, I've been dosing  and 4 ppm of N and 3 ppm of P  /  20 ppm of NO3 and 10 ppm of PO4 for a very long time in both my densely planted tanks and I have excellent plant health and zero algae to speak of.

Cheers,
Michael


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## jaypeecee (10 Jan 2022)

arcturus said:


> This is not about nutrient fearmongering but about scientific evidence. Either there is validated data sustaining that the ratios and their underlying concentrations are irrelevant on a planted tank or there is not.


Hi @arcturus 

Succinctly expressed! 

JPC


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## arcturus (10 Jan 2022)

MichaelJ said:


> It would be great if someone could explain in layman's terms what the crux of the matter is with fertilizer ratios pertaining to our planted aquariums? and what are the postulates either way?  I don't know much about the biological reasoning behind NPK ratios for aquatic plant keeping. For a long time experts around here have been saying that plants don't really care about ratios... that is not to say that you can't lure out some marginal benefits from dosing at certain NPK ratios relative to concentrations, for instance to promote increased algae growth in a laboratory test or promote or suppress algae in radically different environments such as lakes or rivers, but it certainly doesn't seem critically important for a successful planted aquarium.
> For what it's worth, I've been dosing  and 4 ppm of N and 3 ppm of P  /  20 ppm of NO3 and 10 ppm of PO4 for a very long time in both my densely planted tanks and I have excellent plant health and zero algae to speak of.


The main questions are as follows:

Does the ratio of nutrients at a given concentration suppress or promote algal blooms (and plant health)? In particular
What correlations are observable if nutrients are available at non-limiting concentrations?
What correlations are observable if the concentration of one or more nutrients is limiting?
Note: "nutrients" include all elements required for photosynthesis. 

There are laboratory studies and analysis of natural systems that indicate possible correlations between nutrient ratios and concentrations and the promotion or suppression of algal blooms and plant growth. Nevertheless, in discussions related to planted aquariums such observations are often dismissed as being not applicable. Natural environments are certainly very different than planted tanks. This raises a second question: Is the response of a photosynthetic organism (especially algae) to nutrient concentrations and ratios in a planted aquarium similar to the response of the same organism in a natural or laboratory environment? If not, why?


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## MichaelJ (10 Jan 2022)

arcturus said:


> The main questions are as follows:
> 
> Does the ratio of nutrients at a given concentration suppress or promote algal blooms (and plant health)? In particular
> What correlations are observable if nutrients are available at non-limiting concentrations?
> ...


Thank you very much @arcturus for taking time to laying this out in clear terms. That is very helpful! 

Cheers,
Michael


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## jaypeecee (11 Jan 2022)

MichaelJ said:


> It would be great if someone could explain in layman's terms what the crux of the matter is with fertilizer ratios pertaining to our planted aquariums?


Hi @MichaelJ 

I'm pleased that you raised this point. I would like to understand how it applies to the plants that we want* and those we don't want** in our tanks. And what I learned only yesterday is a new term for me. And that is - _Colimitation and Optimal Nutrient Ratios._ If you type the words in italics into a search engine, you should get plenty to read. But, it wouldn't make good bedtime reading. On the other hand, maybe it would. 

* e.g. Java Fern

** e.g. algae and cyanobacteria

JPC


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## MichaelJ (11 Jan 2022)

Thanks @jaypeecee,



jaypeecee said:


> Hi @MichaelJ
> 
> I'm pleased that you raised this point.


I am sure I am not the only one who was curious about the main questions here - always good to reiterate what is being discussed.



jaypeecee said:


> I would like to understand how it applies to the plants that we want* and those we don't want** in our tanks.


Yes, I agree... either way.



jaypeecee said:


> And what I learned only yesterday is a new term for me.  And that is - _Colimitation and Optimal Nutrient Ratios._ If you type the words in italics into a search engine, you should get plenty to read. But, it wouldn't make good bedtime reading. On the other hand, maybe it would.


I did a brief search on "_Optimal Nutrient Ratios for aquatic plants"_ and must say not much came up - However, this one was kind of interesting. According to this, I should have the perfect environment in my tanks for BGA - and I haven't seen BGA for ages and only a bit of it while the tanks were maturing (always thought of BGA as a _new tank_ problem). Of course, It is usually more complicated than one single factor... light intensity, other relevant water parameters and nutrient levels, plant mass, stocking level (i.e. organic waste build up) etc. likely plays a much bigger role than ratios when people are struggling with algae.  But it's an interesting discussion nevertheless.

Cheers,
Michael


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## jaypeecee (11 Jan 2022)

MichaelJ said:


> However, this one was kind of interesting.


Hi @MichaelJ 

A few of us here on UKAPS did an experiment some while ago because we too were interested in the _Redfield Ratio_.  Please take a look at this:






						Cyanobacteria Identification - At Last!
					

Hi again!  Along with the UV-C sterilizer, it will still be necessary to use Easy-Life Blue Exit. May I also request that UKAPS members keep this within UKAPS' four walls? I don't want someone else nabbing the idea and claiming ownership of it. I don't seek to benefit from it other than to...



					www.ukaps.org
				




But, following a lot of reading on this topic, I discovered that the _Redfield Ratio_ was no longer considered to explain the stoichometry of freshwater algae, cyano and plants. At least, that's my recollection but I'll re-visit this soon.

JPC


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## jaypeecee (11 Jan 2022)

MichaelJ said:


> I did a brief search on "_Optimal Nutrient Ratios for aquatic plants"_ and must say not much came up...


Hi again, @MichaelJ 

May I suggest that you try using the search engine, _Google Scholar_? Try exactly the same search, i.e. the same string of characters.

JPC


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## MichaelJ (11 Jan 2022)

jaypeecee said:


> Hi again, @MichaelJ
> 
> May I suggest that you try using the search engine, _Google Scholar_? Try exactly the same search, i.e. the same string of characters.
> 
> JPC


Hi @jaypeecee   yep, that that gives me more relevant results - oddly I didn't use that in the first place as I use scholar.google.com for other matters professionally.


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## ceg4048 (19 Jan 2022)

hypnogogia said:


> @ceg4048, I hear what you say about the ratios, but would it be normal for nitrates to be higher than PO4?


Hi,
    Yes, in the EI scheme of things this is normal. One of the reasons is that much of the PO4 is re-used in various metabolic cycles, whereas generally, the N from NO3 is consumed to a much greater extent by the construction of components such as proteins and so forth. Phosphorous is actually relatively rare in nature and is highly sought after due to it's energy producing capabilities. On the other hand, Nitrogen is abundant in nature. Almost 80% of the air we breathe is composed of Nitrogen, for example. It shouldn't be surprising, therefore, that the relative amount of N versus other elements in organisms is high.


arcturus said:


> I am aware of reports of successful planted tank keepers that seem to show that these ratios are not relevant. But there are other successful planted tank keepers that report otherwise. Are any conclusive (scientific) studies that demonstrate that such ratios do not correlate to algal blooms in planted tanks? Can we dismiss N : P : K ratios, and other ratios such as Ca : Mg?


I'm afraid there is very little conclusive scientific studies demonstrating this. Any study we find is usually focused on natural systems. As you mention, all we have is empirical evidence, based on the results in our tanks. I've personally explored the ratios and have not found any correlation - as long as C, N and P are non-limiting. I've found the same applies to Ca:Mg.


Ria95 said:


> Regardless i have suggested quite straightforward ways to support the hypothesis and form the start of a scientific basis with a series of tests where you can show how important N: P :K is. Others have tried here and there but they still end saying the things i quoted. Plants and algae are adaptable like that, few things break if you go from 4:1 to 3:1 especially when you are speaking about water concentration. Hypotheses abound, rather looking forward to the data. I have referenced the EI source as that is the source of the correct proposal/ratios for EI. Sorry if that offended you but thanks for making the core of your focus clear.


I'm not offended at all. What I try to make clear, especially to inexperienced hobbyists is that because of plants adaptability all we really need to do is to avoid the limitation of nutrients - and by this I mean specifically the EI suggested nutrients. There is another thread where someone attempts to delegitimize EI by substituting ammonium compounds in lieu of KNO3 and reports failure. Well, yes, unlimited ammonium can have negative consequences. I'll repeat what I recall mentioning in that thread, that some hobbyists assume they are reproducing the EI scheme and their failures are then blamed on EI or eutrophic dosing in general.


jaypeecee said:


> Hi @ceg4048
> 
> Please take a look at the following link - Tom Barr's entry. Then scroll down to Roger Miller's entry. I suspect the figures being discussed had their origin in the Redfield Ratio (RR). My understanding is that the RR is now not considered to be applicable to the aquarium ecosystem. At this point, it may be best to go to _The Krib_ discussion:
> 
> ...


Hi jaypeecee,
                      Well, in a way this is kind of a trick question (kinda like when MonaLisa Vito is being cross examined by Prosecutor Jim Trotter in the movie My Cousin Vinny) . I was really only addressing the general EI NO3 vs PO4.
If we extend it to "all forms of N and P that exists in our tanks" then things become a bit foggy. There is, for example N and P bound up in organic waste, in living micro organism, in the sediment and so on and so on. No one can measure or account for all forms of N and P. We certainly can't measure these without specialized instruments, and even so, these values are constantly changing. We can only have precise control of what we dose.
Since I don't have control I'm saying that you can dose as much KH2PO4 as you want and as much KNO3 as you want without worrying about what ratios you dose. So for example you can dose the EI suggested KH2PO4 and then 5X the suggested KNO3 or vice versa. You can also dose any combination in between and not have any trouble as long as you follow the EI scheme regarding cleanliness, maintenance and so forth. Depending on your lighting, you can dose 1/2 EI or 3/4ths in whatever combination. As long as you do not go below the threshold for that lighting level or for the CO2 level then this will work. Members her have done this successfully, many times.  

I think what happens is that we can become so hypnotized by some of these concepts and hypotheses that we lose the thread, so to speak. 
EI also has the world view that neither nutrients nor nutrient ratios cause algal blooms, but that the blooms occur as a result of the conflict between algae and plants in a predator/prey relationship. Barr goes on to explain that malnourished plants are weakened and fall victim to the algae. Blooms can therefore occur as a result of many different scenarios within the tank that causes poor nutrient uptake by the plants in the tank. So blooms occur in a tank and the hobbyists immediately blames too much of this or that, or incorrect ratios, or a score of other possibilities.

Cheers,


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