# Do we really need that much fertiliser ?



## foxfish

I have been using standard EI fertilisation for many years, it has been successful & easy enough, however I was wondering about something.......

Every year I have several emersed tanks growing around my house and in the garden, I have featured them many times on this forum.

 The growth in these tanks can be quite remarkable compared to my water filled tanks.
 I know the main reasons for the lush & fast growth is based around the amount of available C02 & the massive amounts of light the tanks receive from the sun.
However I hardly fertilise  these tanks at all!!
Sometimes I add some natural based fertiliser like chicken manure or even a few beads of slow release fertiliser into the original soil mix but, I most certainly don't add spoons full of powder every week!

I know all about the EI concept & I have no issues about using the method but, I do wonder if I really need to use only a small fraction of what I actually dose?

There are many members who regularly discus using 'double EI' or adding extra 'this or that' to their mix to avoid algae etc.
 I was just wondering why my emersed plants grow so well with hardly any fertiliser if aquarium plants require so much when under water?


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## dw1305

Hi all,


foxfish said:


> I know the main reasons for the lush & fast growth is based around the amount of available C02 & the massive amounts of light the tanks receive from the sun.
> However I hardly fertilise these tanks at all!!
> Sometimes I add some natural based fertiliser like chicken manure or even a few beads of slow release fertiliser into the original soil mix but, I most certainly don't add spoons full of powder every week!
> 
> I know all about the EI concept & I have no issues about using the method but, I do wonder if I really need to use only a small fraction of what I actually dose?


I think the simple answer is "_yes you could use much lower levels of fertiliser dosing_". There will be a few plants that need everything (light, warmth, nutrient levels) _<"turned up to 11_">, but most will do with less.

You would need to ask Tom, but I think the original premise was that nutrients would be non-limiting, so it doesn't matter if you have too much, but you need to be in the "Adequate zone" of the nutrient curve (for all the elements <"necessary for plant growth">) for the most nutrient demanding plants (From <"_Rotala_.....">).







If you don't care how quickly they grow you can keep Ferns, _Anubias_, Mosses etc in water that is basically RO with a trace of nutrients, as long as you have all of the essential nutrients.

I just want to keep my plants in growth, I don't want them growing quickly and I keep a limited range of "low light" plants. Because of this I can use the Duckweed Index, my duckweed (usually _Limnobium_) has access to atmospheric CO2, and it will grow across a wide range of water conditions. As long as I keep the _Limnobium_ in growth I have enough nutrients for the submerged plants.

cheers Darrel


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## JMorgan

Hi Darrel - though I think I've read most of what you've posted about the duckweed index, I wonder if I've missed some info where you've possibly commented on how one might interpret different 'symptoms' as seen with _Limnobium ?
_
For example in one of my tanks the majority of the _Limnobium_ leaves are a good strong green but I seem to be forever picking out single leaves that have somehow detached from the main plant. These themselves can be a good shade of green, but over time turn yellow and eventually melt to a brown sludge - while other intact plants are obviously thriving. It's possible that this is just mechanical damage as the frogbit gets moved about by fish and the filter, though the latter is a mild as I can make it, but for all I know it could be a classic indicator of something I'm unaware of.

Also to what extent is the yellowing of the older leaves that are gradually covered over and even submerged by newer growth an indication of anything, and to what extent is it just a natural process?
Any other tips on how to interpret clues from _Limnobium_? Other than colour and growth - for e.g. in some of my tanks the frogbit seems to grow much bigger leaves, as to making many more but smaller leaves? Some grow magnificent "bushy" roots while others put out tremendously long thin roots?


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## ceg4048

foxfish said:


> I know all about the EI concept & I have no issues about using the method but, I do wonder if I really need to use only a small fraction of what I actually dose?


No, it is not always necessary, in fact rarely necessary for survival.

Even folks who have been using eutrophic dosing schemes have forgotten or had not considered the origin and purpose of the scheme.
When people first hear about EI, or PMDD, or ADA, or whatever they cannot be bothered to study concept, history or purpose, so they just use the numbers and they get on with the dosing, so it becomes a numbers game. I was on a major rant the other day about the preponderance of all these web based nutrient calculators. All it takes is for the user to input garbage numbers and the output is a garbage scheme. Without any kind of understanding of the basic idea numbers, most folks are completely incapable of determining the validity of the results or how to arrive at basic concentrations values, so they do not know whether the calculator is giving them truth or blahblahblahblahblahblah.

As Darrel mentions, the basic idea is that Tom (plantbrain) derived the values to be non-limiting, so that even under the highest possibnle conditions of lighting and CO2, maximum growth rates could be achieved. Under those conditions, increasing the dosage did not result in significant increase in growth rate.

So the EI dosing levels are at the very top of the nutritional requirements under the very highest of stressful conditions.

Therefore, of the dosing program is at it's maximum capability to support growth, any failure of growth and health could not be attributable to the dosing program and therefore the hobbyist would need to look at other aspects of the tank system for faults, such as flow/distribution, CO2 and so forth.

One of the major tenets therefore is that if you are dosing EI levels of nutrients and the tank suffers a nutrient related fault, then the answer cannot be that there is a nutrient dosing shortage.

The EI dosing level addresses the high end of the spectrum but nowhere is it stated that the levels cannot be modified to fit the conditions. If the tank is operating at a moderate level then the dosing can be modified to moderate levels, but it is always a good idea to start at the top level and to then work your way down. This enables better troubleshooting if things go wrong. The point is that EI does not have specific dosing numbers for moderate or low levels of lighting stress or low levels of CO2 injection, so it has to be derived for each person through experimentation.

Tom does have dosing suggestions for low tech, non CO2 enriched tanks. The values are very small as befits the low growth rates in low tech tanks.

As far as multiple dosing goes, it really isn't necessary at all. I do it specifically to debunk the myths about nutrient toxicity.

Cheers,


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## BubblingUnder

JMorgan said:


> forever picking out single leaves that have somehow detached from the main plant


Surely that's just their way of reproducing & could be blown somewhere else in the river/lake to start again.


JMorgan said:


> over time turn yellow and eventually melt to a brown sludge - while other intact plants are obviously thriving


I would have thought that decaying Frogbit would release nutrients back into the water which would then be available to other plants including the remaining Frogbit which could then recover for a period of time (although their would be fewer & smaller frog bits).


JMorgan said:


> Also to what extent is the yellowing of the older leaves that are gradually covered over and even submerged by newer growth an indication of anything


I would have thought that it just indicates that it is growing in a limited water surface area i.e. _an aquarium not a river or lake.
_
I'm not an expert but the 'duckweed index' is quite interesting & would seem to make sense (if I have interpreted correctly).


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## Paulo Soares

ceg4048 said:


> Even folks who have been using eutrophic dosing schemes have forgotten or had not considered the origin and purpose of the scheme.
> When people first hear about EI, or PMDD, or ADA, or whatever they cannot be bothered to study concept, history or purpose, so they just use the numbers and they get on with the dosing, so it becomes a numbers game. I was on a major rant the other day about the preponderance of all these web based nutrient calculators. All it takes is for the user to input garbage numbers and the output is a garbage scheme. Without any kind of understanding of the basic idea numbers, most folks are completely incapable of determining the validity of the results or how to arrive at basic concentrations values, so they do not know whether the calculator is giving them truth or blahblahblahblahblahblah.



 Precisely!


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## AverageWhiteBloke

JMorgan said:


> Hi Darrel - though I think I've read most of what you've posted about the duckweed index, I wonder if I've missed some info where you've possibly commented on how one might interpret different 'symptoms' as seen with _Limnobium ?
> _
> For example in one of my tanks the majority of the _Limnobium_ leaves are a good strong green but I seem to be forever picking out single leaves that have somehow detached from the main plant. These themselves can be a good shade of green, but over time turn yellow and eventually melt to a brown sludge - while other intact plants are obviously thriving. It's possible that this is just mechanical damage as the frogbit gets moved about by fish and the filter, though the latter is a mild as I can make it, but for all I know it could be a classic indicator of something I'm unaware of.
> 
> Also to what extent is the yellowing of the older leaves that are gradually covered over and even submerged by newer growth an indication of anything, and to what extent is it just a natural process?
> Any other tips on how to interpret clues from _Limnobium_? Other than colour and growth - for e.g. in some of my tanks the frogbit seems to grow much bigger leaves, as to making many more but smaller leaves? Some grow magnificent "bushy" roots while others put out tremendously long thin roots?


I think this is where EI comes into effect, it eliminates the guess work out of fertilisation. If you suspect that there are some issues just dose full EI for a month or so and see if anything changes. It's part of the elimination process. I think combining the two methods EI/DWI is the two most useful tools we have at our disposal better than any tests or DC'S which are at best a rough idea. It enables us to actually use the plants which are far better indicators.
In the case of DWI you can narrow down to fert issues and EI narrow down to co2 flow issues so outside of tank cleanliness you can gauge where things are going wrong. I suppose we have to look at EI as a bit of an idiots guide to growing plants so shouldn't be made complicated as it was designed to simplify things. 

I do understand the EI calcs because it gives people something tangible, especially when we start getting down to sub 100 ltr tanks and dealing with 1/32 of a tspoon of po4. 

However.like mentioned, chances are the vast majority of us are not going to need the doses with our particular lighting so it comes down to using the two techniques to try and work out how much we do need...if you want to. In my particular case I try and keep my TDS down a bit for the sake of the fauna and inevitably with full EI dosing that will rise because you are never going to be using it. I just counter this with a smaller dose now and again or even better an extra WC.

Coming back to plants, sometimes plants just get damaged or grow an odd shaped leaf now and again, it happens, just cut it off if it offends you, often leaves will get damaged doing wc's and maintenance, maybe snapping a stem which then dissolves and everyone's first panic reaction is omg not enough potassium or whatever. I've looked at a few images of real water courses with plants in looking for inspiration for shapes and you'll be shocked at how many wild species have holes in leaves or brown tips and these plants chose to live there, no point asking God if he can take a look at the Andes and see if there's enough potassium coming down there. 

I think it's best to look at plants in the main, you maybe have the odd couple exhibiting something but in the main what are they like. I get certain leaves on Duck weed that aren't optimum but in general they are doing fine so therefore I assume my dosing is fine. Having very soft water and adding some iron root tabs as well as traces iron or chlororis  in new leaves is rarely a problem although there are a few new leaves that are a bit pale. Old leaves tend to be more problematic with me holding back a bit of Magnesium for tds sake. If all other plants seem fine then I carry on as normal, and signs anywhere else I chuck in another quarter teaspoon of Epsom salts. I tend to find if DW is low on nitrogen they get lines on the leaves but rarely happens with dosing about 2/3rd of EI values.

As for co2, I also have other test plants so I combine the DW with this to get an overall picture and like Darrel I look for growth, if I'm seeing growth then things in the main are doing ok.

Some examples would be, if I take a look in my tank mid week, firstly the duck weed..

Few lighter leaves here and there, most of the yellowing ones were removed at weekend but in the main they're OK so no need to panic.

Then there's the Java fern there, notice the dark green tips, a sign of new growth. 

Apologies for not knowing what the other plant is (I'm useless with plant names) but that is put there deliberately. It's been put in a place I would suspect of having the worst co2. Usually once a week, maybe two I would trim it down to about an inch off substrate level. In a week I would hope for this thing growing an inch or two. Same plant gratuitous bobbling shot haha

My MC carpet I look for new growth on the tops, yes there's a bit of algae in there but it's not taking over so no need to be looking for remedies just yet, it's just part of keeping a tank in my eyes.

I guess what I'm saying is people seem to be looking for problems for the least thing and in a healthy aquarium you are going to get a bit of algae and the odd poor looking plant, doesn't always mean you are doing something wrong. We're trying to create a water body scene and you will find all those things in there, it's not binary right or wrong, there's plenty in between just like EI dosing.

As long as things are growing I tend to leave well alone and concentrate on cleaning.

Just thought I'd put a picture of my GBR in as well for good measure. I couldn't get a picture of any of the plants there without them getting their mugs in so obviously Naomi Campbell and Tyson Beckford wanted to be part of the shoot haha













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## AverageWhiteBloke

Couple of GBR shots, apparently I caught them on their bad sides  love these fish when they are not falling out. 













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## dw1305

Hi all, 





BubblingUnder said:


> I'm not an expert but the 'duckweed index' is quite interesting & would seem to make sense





AverageWhiteBloke said:


> ......and like Darrel I look for growth, if I'm seeing growth then things in the main are doing ok.
> 
> Some examples would be, if I take a look in my tank mid week, firstly the duck weed..
> 
> Few lighter leaves here and there, most of the yellowing ones were removed at weekend but in the main they're OK so no need to panic.


Like @AverageWhiteBloke says it is just a technique where you use a floating plant (so it isn't CO2 limited) as an indicator of nutrient status.

As long as the plants are growing you you just carry with water changes etc. when the floating plants look less healthy you feed them.

I used Lesser (Common) Duckweed (_Lemna minor)_ initially because it is the <"plant used for bioassays of polluted water">, but it has the disadvantage of not doing well in soft water with low nutrients, so now I use Amazon Frogbit (_Limnobium laevigatum)_ as my "duckweed".
It will grow over a whole range of water conditions.

The only real disadvantage of using the Duckweed Index is that by the time deficiency symptoms for non-mobile nutrients (nearly always iron (Fe)) show on the youngest leaves (image below, from @jameson_uk's <"thread"> ), the plant has been iron deficient for some time, and the plant will only green up again when it grows new leaves.





cheers Darrel


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## JMorgan

Thanks Darrel - I do understand the broad principle, but I also think I'm probably missing a few clues that other more experienced people would think of as obvious in 'reading' the health of my frogbit. Now I've seen the picture above re Iron deficiency I have another snippet to file away. 


AverageWhiteBloke said:


> I think it's best to look at plants in the main, you maybe have the odd couple exhibiting something but in the main what are they like. I get certain leaves on Duck weed that aren't optimum but in general they are doing fine so therefore I assume my dosing is fine.



Understood - I'm more intrigued and interested than worried about anything as - _in the main_ - all the frogbit is growing. However it grows differently in different tanks and I'm curious to understand why _better_. I don't _need_ to know, in fact since my knowing more detail is unlikely to produce a more sophisticated response than an extra squirt or two of DIY all-in-one ferts, it's true to say my knowing is pretty irrelevant to the plants. So I just thought I'd list some things I'd noticed and see if it rang any bells


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## dw1305

Hi all,





JMorgan said:


> However it grows differently in different tanks and I'm curious to understand why _better_.


This is healthy _Limnobium (& Lemna). _(From @tayloss's <"Free - Amazon Frogbit"> thread).

Mine never looks this healthy in the tanks, although it sometimes does in the glasshouse in the summer with more nutrients, warmer water and a lot more light.

_




_
The Amazon Frogbit that had really been pumping iron (and everything else) was @Timon Vogelaar's (below) (from <"An Iwagumi .....">)





cheers Darrel


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## AverageWhiteBloke

JMorgan said:


> Thanks Darrel - I do understand the broad principle, but I also think I'm probably missing a few clues that other more experienced people would think of as obvious in 'reading' the health of my frogbit. Now I've seen the picture above re Iron deficiency I have another snippet to file away.
> 
> 
> Understood - I'm more intrigued and interested than worried about anything as - _in the main_ - all the frogbit is growing. However it grows differently in different tanks and I'm curious to understand why _better_. I don't _need_ to know, in fact since my knowing more detail is unlikely to produce a more sophisticated response than an extra squirt or two of DIY all-in-one ferts, it's true to say my knowing is pretty irrelevant to the plants. So I just thought I'd list some things I'd noticed and see if it rang any bells


Maybe lighting could be a factor mate if you notice them looking different in different tanks. When my tank was running with nothing but daylight I found they seemed to have a smaller root system. I built the light back up gradually over a couple of months and find myself back at 100% lighting (for now anyway) when I was running at 50% The leaves weren't as big as they are now but still healthy in colouration. I first ran into issues when I significantly lowered dosing for a while and they appeared to get stripes. This went away when I upped dosing but is still visible on some of the older leaves. There's a bit of a  delay so anything you notice now will actually have been something that was low a week or so back I guess. So keep an eye on how how the new growth looks, the old growth is history.

Mine have always ditched older leaves even in good health, maybe that's just how the plant functions. If old leaves look a bit ropey maybe try a little bit of Epsom salts and see if that improves the situation, you don't need much.

Mechanical damage can't be ruled out. When I do water changes I take mine out and put them in a tupperware  box, it makes it easier after trimming my carpet plants to net out the cuttings and when finished I put back usually only the bigger specimens, the smaller ones tend to get stuck in my surface skimmer. Maybe I damage the quite fragile stems doing so and that's why they lose leaves. 

Could it be you're running out of nitrogen? Plants are dividing up into smaller ones but never really get enough to grow large, as you say, only a couple more squirts will prove that. 


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## AverageWhiteBloke

dw1305 said:


> Hi all,This is healthy _Limnobium (& Lemna). _(From @tayloss's <"Free - Amazon Frogbit"> thread).
> 
> Mine never looks this healthy in the tanks, although it sometimes does in the glasshouse in the summer with more nutrients, warmer water and a lot more light.
> 
> _
> 
> 
> 
> 
> _
> The Amazon Frogbit that had really been pumping iron (and everything else) was @Timon Vogelaar's (below) (from <"An Iwagumi .....">)
> 
> 
> 
> 
> 
> cheers Darrel


They are looking healthy! Totally different to the ones in mine but mine are just starting to make a come back. 

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## tayloss

Believe it or not, this is the tank I almost neglect and change water one every two weeks... 

Thanks for the compliments Darrel 


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## AverageWhiteBloke

tayloss said:


> Believe it or not, this is the tank I almost neglect and change water one every two weeks...
> 
> Thanks for the compliments Darrel
> 
> 
> Sent from my iPhone using Tapatalk


Maybe that's it, they prefer a dirty tank with plenty to eat. Without co2 holding them back they can just get on with feeding and converting this in to plant mass. 

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## AverageWhiteBloke

Just an observation, been looking at mine and @tayloss his appears to grow out and away from the centre of the plant whereas mine seem to grow over the top of each other. It would appear that the yellower leaves are the ones underneath and these tend to be the ones that fall off. Going off one of Darrels recent post perhaps the plant is sacrificing a leaf that gets less light in favour of one that gets more? 

Sort of makes sense for the plant to do that so perhaps it would be an idea to regularly pick off these leaves and let the plant concentrate it's energy on ones that stand more of a chance. 

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## kadoxu

AverageWhiteBloke said:


> Maybe that's it, they prefer a dirty tank with plenty to eat. Without co2 holding them back they can just get on with feeding and converting this in to plant mass.


I believe it's not only that... stability is very important as well, so the less you mess with it, the more the plants will thrive.


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## tayloss

It seems to be the only thing i can grow successfully during my planted tank experiment  Its also under a very bright LED lamp, so this may also help in the rapid growth! what I don't understand is I have had the frogbit for over 6 months growing out, and all of a sudden the duckweed appeared! Its a master of surprise and hiding I guess or can it come from some other source?


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## dw1305

Hi all, 





AverageWhiteBloke said:


> It would appear that the yellower leaves are the ones underneath and these tend to be the ones that fall off. Going off one of Darrels recent post perhaps the plant is sacrificing a leaf that gets less light in favour of one that gets more?


Yes I think that is reasonable suggestion. In the glasshouse the leaf rosettes tend to be very tight with a short petiole (the stalk) and a very thick laminar.

This is a high light, and the aerenchyma (the "float" cells) was x3 as thick as in the cross section below. 






In the the tanks the petioles are always longer and the laminar thinner, and in the tank with a lid, as soon as the leaves become crowded they change morphology and become the aerial leaves, and the plant flowers.

cheers Darrel


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## Edvet

Frogbit in my tank a few years ago, with Phyllantus fluitans and Ceratopteris pteroides. I was only dosing NO3 as i remember, but also feeding hard so probably plenty PO4 too


39891049_00005534JPEGof by Ed Prust, on Flickr


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## AverageWhiteBloke

Starting to suffer from Frogbit envy now  I think we should have a bit of a Frogbit competition like they do with those massive pumpkins  Side effect of the competition will be the rest of your plants will love it..which can't be a bad thing.


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## dw1305

Hi all, 





AverageWhiteBloke said:


> Frogbit envy now  I think we should have a bit of a Frogbit competition like they do with those massive pumpkins


I must admit this thread has given me Frogbit envy as well, but I think that is the start of the slippery slope, and nothing but heart-ache lies that way.
*
However* if I was going to to go down the "_my frogbit is bigger & better than your frogbit" _route:

I would wait until next summer, make sure it gets plenty of sun-light (on a window-sill, or even better, outside) and grew it in shallow water, with a nutritious bottom, and lots of nutrients in the water column. 

You can see thick white roots on the high light plant (in my photo earlier in the the thread) these had grown once the plant was anchored to the substrate.

This (or even bigger) should be possible, (from <"University of Florida - Center for aquatic and invasive plant species">).







cheers Darrel


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## sparkyweasel

I would put mine in my low-down pond, where watercress grows huge, green leaves, but no-one wnats to eat them. In the higher pond it grows smaller, paler leaves, but people will eat them. The reason for both differences is that the dogs can reach to wee on the lower one.


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## tayloss

sparkyweasel said:


> I would put mine in my low-down pond, where watercress grows huge, green leaves, but no-one wnats to eat them. In the higher pond it grows smaller, paler leaves, but people will eat them. The reason for both differences is that the dogs can reach to wee on the lower one.



Ha! Can understand why ... 


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## plantbrain

Ya'll know , do we really NEED CO2 gas enrichment? Or NEED high light? Well, depends on your goal, but the generally answer is certainly a resounding no, you do not. 
Folks love the haggle about ferts, but not CO2, or light, even though those are the two main drivers.


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