# Couple of N related questions



## Ravenswing (13 Jan 2013)

Hello!

I have come from high to low last spring and everything has gone pretty well but every now and then I find myself thinking some strange things like...

1) I have used almost an year root tabs wich are made for houseplants. They contain ammonium. There hasn`t been any problems with them thou sometimes my cories dig then up (they love them!!) but now Im bit worried since my KH is pretty low, 2 (also tap), and I raised it a bit so pH is now 7,6 or more (JBL test ends 7,6). pH has been earlier 7,2-7,4. I use EC. But...It is said that ammonium will turn to ammonia rapidly so is there possibility for that now pH is that high? On the other hand Iv been thinking no to touch KH/pH at all since they have been stable for months, so why bother since plants seems to do pretty fine...? It just sounds so low and as we used to have pressurized Co2s Im used to keep it higher (4-5) but nowadays we dont have pressurized systems anymore so this is new situation for me.

2) A bit confused... In a thread wich I red totally tired (>cant find it now) one night Gec states that (over)dosing NO3 will increase the demand of CO2. Maybe/propably I was too tired to get the point but havent we been taught that according to EI you can keep excess of nutrients even in tanks without Co2 and there is only one nutrient (not counting light now) that can be used to restrict the demand of Co2 and that nutrient is PO4. I dont use gasCo2 but EC so Im interested in if the slight excess of NO3 Im keeping on really causes increase demand of Co2 wich is, I guess, on the edge right now in my tanks. Im not using PO4 (tried without any visible signs of nothing) so IF excess of NO3 will increase the demand of CO2, maybe I have to limit NO3 too (kept it stable 5mg/l)?


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## ceg4048 (14 Jan 2013)

Hi,
   Not sure why you think that PO4 does not affect CO2 demand, but NPK are coupled either directly or indirectly to CO2. That's one of the reasons non-CO2 enriched tanks don't use such high levels of dosing. Using liquid carbon = CO2 so if you don't use enough of it then it's that level of CO2 that would limit your growth rates. That's one possible reason adding more PO4 may not have had a visible effect.

It's not clear at all what problem you are having.
What is the tank configuration, what are your dosing procedures, and what is the lighting? Sorry, but can you re-state the problem?

Cheers,


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## dw1305 (14 Jan 2013)

Hi all,


Ravenswing said:


> I have used almost an year root tabs wich are made for houseplants. They contain ammonium. There hasn`t been any problems with them thou sometimes my cories dig then up (they love them!!) but now Im bit worried since my KH is pretty low, 2 (also tap), and I raised it a bit so pH is now 7,6 or more (JBL test ends 7,6). pH has been earlier 7,2-7,4. I use EC. But...It is said that ammonium will turn to ammonia rapidly so is there possibility for that now pH is that high?


No you can ignore the NH3 or NH4+, in my heavily planted tanks I usually add liquid fertilisers with NH3NO3 without any problem. Because the root tabs are "slow release" any ammonia/ammonium will be mopped up straight away.


Ravenswing said:


> On the other hand Iv been thinking no to touch KH/pH at all since they have been stable for months, so why bother since plants seems to do pretty fine...?


 No keep on doing what you have been, you can ignore dKH/pH as well. pH is inherently unstable in soft water, relatively small changes in the H+ ion donor (acids) and H+ ion acceptor (alkalis) number cause large changes in pH, because pH is just the ratio of H+ donor: H+ acceptors and tells us nothing about amounts.


Ravenswing said:


> according to EI you can keep excess of nutrients even in tanks without Co2 and there is only one nutrient (not counting light now) that can be used to restrict the demand of Co2 and that nutrient is PO4. I dont use gasCo2 but EC so Im interested in if the slight excess of NO3 Im keeping on really causes increase demand of Co2 wich is, I guess, on the edge right now in my tanks.


In any restricted system one element will be limiting, the idea behind EI is that there is always sufficient nutrients (including CO2), and the input of light energy limits growth.


Ravenswing said:


> Im not using PO4 (tried without any visible signs of nothing) so IF excess of NO3 will increase the demand of CO2, maybe I have to limit NO3 too (kept it stable 5mg/l)?


Even though P is one of the macro-elements plants actually need much less of it than they do of either N or K, so it is unlikely that plants will be phosphorus deficient. I use nutrient reduction (fertiliser addition is via the "Duckweed Index" <Water Lettuce and it's impact on my tank | UK Aquatic Plant Society>), but this limits potential plant growth and the range of plants you can grow.


ceg4048 said:


> It's not clear at all what problem you are having.


 Would we be right in thinking that you don't have any plant growth issue at present? if you don't? I'd just carry on with what you have been doing.

cheers Darrel


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## Ravenswing (14 Jan 2013)

Hi!

Thank you both and I must apologize my poor way of express myself.

No/yes, I dont have any problems now, just trying to avoid them. Thinking (but not worrying!) propably too much but Im also eager to learn. I know that limiting PO4 we can limit the demand of CO2 but I just became confused because of the thread were Ceg states that adding (too much?) NO3 we will increase the demand of CO2. Maybe I should try to find the thread, read it again carefully and then ask more specific questions if needed.

DW: Thanks for your help again! As you might remenber, my tap water EC is quite high ca 620uS (inc. NaOH&NaCl) but GH is pretty low, tap 4, tank 2-3 before WC. I use DIY-Equilibrium to keep it at 4(-5) since it seems to go down pretty fast. Do you think this will be just fine and I can ignore low KH (2). Last spring I got a slight plant catastrophe with some species (pressurized CO2 and metalhalides, EI without GH-extra. Stupid me) since I ignored GH as I was advised to do so because "it is so high" and "it wont change". Well after couple of months it was zero and few species were melting away....I found it easier to add it a bit with every WC. KH has always been pretty stable but whe we had gasCO2, I kept it at 4-5 with baking soda. I have to read about Water Lettuce-method more, thanks for the link.

Edit. How about NaCl and NaOH, what fish or shrimps like them about?


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## ceg4048 (14 Jan 2013)

I had a quick search and found the thread Is there any need for a rest day in EI dosing? | UK Aquatic Plant Society which gives a simplified schematic of the demand relationship. If I use the expression "too much" in the context of an EI tank it's normally related to too much light which drives the demand for nutrients or too much of one nutrient revealing that there is a shortage of another. As Darrel points out, only one nutrient at a time causes a limitation. The speed of growth encounters one limitation at a time. If the light is kept very low then at some point you can add loads of everything else, but the low light level will be the limiting agent, for example.

On the other hand there is a range of nutrient concentration values that the plants are able to adapt to. So it can easily be that there is sufficient "headroom" in the system, but that there is potentially one nutrient that, if everything else is increased, that nutrient will become the new limiter.

When plants uptake CO2 they have to do something with it. They build molecules. Food molecules, structure molecules, protein molecules and so forth. But molecules are comprised of other elements such as N, P, and K. So if I substantially increase CO2 then the natural progression for the plant is to increase food to grow, but to grow, it must make protein molecules which are made from C and N & P. So what happens if I don't add lots of N? Then I cannot complete construction of protein even though I have a surplus of C. The protein molecule would be incomplete and would not function as intended. So adding more CO2 will expose the low N. This will be independent of how much K and micros are available. The limiter changed from C to N. Similarly, to build certain molecules using C and N the plant must also add P. For example DNA is a molecule which uses lots of P. So if I now add plenty of CO2, plenty of KNO3, no matter how much of those I add, I still am limited in the amount of DNA that can be built because of a lack of P, even though the addition of extra CO2 triggers an upsurge for DNA replication. The food that plants make using photosynthesis is a sugar, built with C and N, but it is a special kind of sugar, a high energy sugar, a Phosphate sugar. Restricting P while adding a lot of everything else exposes the fact that P is low because the demand for P will rise when light, C and N are increased. So if you severely restrict P, the plant can still suffer starvation even though you are adding lots of C and N.

So, if you are using EasyCarbo, which is the same as using CO2, only less so, then there is a demand for everything else, but if you decide to restrict any of the rest, at some point, depending on how much of the other things you add, adding more of those will reveal the weakness in the item that you decided to restrict.

Many people see this phenomenon and they interpret it incorrectly. In a way it reinforces the belief that adding certain nutrients causes algae. Adding CO2 to a tank causes all kinds of grief because people don't really understand this principle of limitation and increased demand. Hope this clarifies a little.

Cheers,


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## Ravenswing (15 Jan 2013)

Hi ceg!

Yep, I got your point. I must have missunderstood something in the thread mentioned because im familiar with everything you state above. Id like to find the thread since it was really interesting anyway! I must thank you for your posts, Iv learned a lot of them! Im a just graduated professional gardener but some phenomenons in aquariums makes me still confused. Algaes are in control but there is so much to learn when it comes to nutrients and correlations between them, CO2, light, water parameters etc.

Cheers, Maria


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## ceg4048 (15 Jan 2013)

Hi Maria,
			Wow, I'll bet you are an excellent aquascaper in that case.  Glad you find the data useful and interesting. I might easily have misstated something or explained it poorly in the post in question. The last I recall talking about this issue was when someone wrote that they were having, what appeared (to me) to be a CO2 deficiency issue, and they decided that doubling their NPK was a good thing to do just in case. I recall having explained that since adding NO3 increased the demand for CO2, it was not really a good idea to exacerbate a CO2 deficiency by increasing the plant' demand for it by adding more nutrients, especially if the tank was not suffering any NPK shortfall. This is normally when folks get confused because I'm always prattling on and on about adding more nutrients. 

Cheers,


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## Ravenswing (17 Jan 2013)

ceg4048 said:


> Hi Maria,
> 
> Wow, I'll bet you are an excellent aquascaper in that case.


 


LOL, definetly not, and for sure the playgrounds between garden plants and aquarium plants differs and give some different kind of challenge. Weeds are piece of cake compared to algaes! Eh, I know what you mean by saying "...always prattling on and on about adding more nutrients" . After that people think its always a solution for everything but however its not in every case. After saying something different as usual people are confused as they dont see the whole puzzle and can`t understand the correlations between things. Not an easy job, but so cool you keep doing it! Unfortunately we here in my homecounry still advice hobbyists avoid The Bad Po4, to keep nutrient levels as low as possible, CO2 is either a "miracle thing", "does nothing" or it "surely will kill your fish" etc etc. So good to read a forum like this were things keep running forward, not backwards! Looking forward to read more of your and other hobbyists with strong knowledge posts.

Cheers, Maria


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