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EI - Dosing Just P & K

Tim Harrison

Tim Harrison

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UKAPS Team
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I was considering using EI on my next venture; I’ve always used TNC Complete. Out of curiosity I had a look at my water quality report…

Nitrate 15.61mg/l
Potassium 7.99mg/l
Magnesium 7.49mg/l
Phosphorous 7.62ug/l

The figures are yearly averages. Nitrate and Magnesium values seem to be pretty close to EI values.
With this in mind, what would be the best way of adding the required potassium and phosphate?
That is if I've understood all this correctly...chemistry was never my strong point.
 
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Your water report is for the water companies test point on a particular day and is not your tap today. Ignore the report and just dose EI you are heading down the route to plant deficiencies and algae if you choose to follow this path to disaster.
 
...But just out of interest, assuming this was actually my tap water, what would be the best way of making up the shortfall in the other nutrients?
 
Just dose EI as you cannot assume or measure accurately what is in your water. If your water does have this, doesn't matter your plants will have extra which is not a problem.
 
Troi said:
...But just out of interest, assuming this was actually my tap water, what would be the best way of making up the shortfall in the other nutrients?
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Agree with Ian, water reports are far from being what you really have the rest of the days of the year in your tap water. Whatever you chose, EI or lean dosing scheme, do forget about your water company analysis. 6 months ago I bought a TDS meter and since now I have measured different values between 1,000 and 640 microsiemens.... Not bad, isn't it?

Jordi
 
Seriously guys thanks, and I hear you 100%...I was just curious which inorganic compound would do the job out of sheer interest...
 
I would like to know this too! But I'm guessing that you can't adjust one specific nutrient without affecting the other. This is despite what ferts manufacturers advertise e.g. ADA Brighty K is still simply a weak solution of KNO3 and/or KH2PO4. it can't only contain K.

Nethertheless, in this great video
()
the author talks about maintaining specific levels of nutrients. Confusing!
 
I don't even want to comment here Troi :p You can't be going by the numbers. You want to watch your plants. :) I guess you had something else in mind though and I am only joking :p
But yes, if you want to test out if your water report has some leverage, why don't you? Just dose what you think your tank would be theoretically lacking...
 
Yep, genuinely thanks guys...I'm trying to be clever, they are only average values and the max/min is pretty erratic for nitrates but pretty even for magnesium...but perhaps I'm trying to be too clever...
Anyhow, my chemistry is poor and I can't be bothered to swat up...so I was hoping one of you guys could give me a sort cut...perhaps Darrel or Clive will have something to add...
 
Troi said:
Yep, genuinely thanks guys...I'm trying to be clever, they are only average values and the max/min is pretty erratic for nitrates but pretty even for magnesium...but perhaps I'm trying to be too clever...
Anyhow, my chemistry is poor and I can't be bothered to swat up...so I was hoping one of you guys could give me a sort cut...perhaps Darrel or Clive will have something to add...
Click to expand...

Based on ceg4048's article, this is the target:

(per week)
NO3 20 PPM
K 30 PPM
PO4 3 PPM
Mg 20 PPM

And these are already in your water:

NO3 15.61 PPM (-4.39)
K 7.99 PPM (-22.01)
PO4 0.00762 PPM (-2.99238)
Mg 7.49 PPM (-12.51)

To reach the values in the article, add:

(per week)
KNO3 0.00716 grams per litre
K2SO4 0.04011 grams per litre
KH2PO4 0.00428 grams per litre
MgSO4.7H2O (Epsom Salt) 0.1264 grams per litre
 
Troi, as mentioned I do not pay much attention now to my water company analysis, just to the conductivity. I found the tank management to be easier when the conductivity is about 400 microsiemens, don't know why but it works very well.
I've been dosing for three months just K and micros (20ish liters tank with AquaSoil). But without paying too much attention to the amounts. For example, my Potassium sulfate solution was in a glass container and I was dosing with a syringe 0,5 ml a day according to my calculations, but then I found a cool soap dispenser (a plastic one very similar to the ones used by ADA/Tropica for their fert lines) so I decided to recycle it. Each squirt makes a bit more than 1 ml, so I decided to dose this instead of the 0,5ml. The same with micros... It is a daily dose that is between 0,5 and 1 ml. Of course when I'm traveling I don't fertilize. And in the last water changes I've tried to add some drops of Tropica Specialized (the one with N and P).... In other words, my piece of advice would be: rely on a good substrate, find the sweet point with co2 and light and do forget about fine adjustments regarding fertilizers. Plants need them but that all, no need to make from it something very complicated.

Jordi

Edit: it reminds me a little bit my other hobby, homebread baking. At the beginning you need to measure everything but it is useless as every flour absorbs water at the different rate and behaves very different during the kneading... But after some time you just know when the dough is ok, you respect some rough numbers in your recipe but just as a guideline
 
Hi all,
parotet said:
I found the tank management to be easier when the conductivity is about 400 microsiemens, don't know why but it works very well.
Click to expand...
I do the same, if the tanks are about 80 - 150 microS, then both fish (I keep Apistogramma etc.) and plants are fine, again I've got no idea of why this works.
sciencefiction said:
You can't be going by the numbers. You want to watch your plants.
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Works for me, I just used a floater to remove CO2 from the equation.

Most deficiencies are either N or K (plants need x10 more of these than any of the other nutrients), followed by P and Mg. I would suspect that those 4 elements cover 99% of deficiencies, with the vast majority being N and/or K. Magnesium (and iron) are slightly different in that if deficiencies occur they are likely to be to do with the hardness and calcium content of the water (Ca:Mg ratio etc), rather than actual values.
Troi said:
I'm trying to be clever, they are only average values and the max/min is pretty erratic for nitrates but pretty even for magnesium
Click to expand...
Element levels will depend upon the source of the water, your local geography and agricultural land use. The magnesium source would be from the local geology, there aren't really any other sources. If your water is entirely from an aquifer Mg levels will remain fairly constant, if you have river or surface water (from a reservoir etc.) levels may vary a bit, but not very much. If your calcium level is also fairly constant? you are probably getting mainly aquifer water.

Most of the other major nutrients will have a range of sources. Potassium will come from agricultural fertilizers and possibly the local rock, phosphates will come from agriculture, optical brighteners from treated sewage and the orthophosphate that water companies add to the water supply and nitrogen will come largely from sewage treatment and agriculture.

You get an annual "rhythm" to the levels of all these nutrients, generally levels will be lower in the winter when you are getting more rainfall to dilute sewage treatment water and top up shallow aquifers, peaking in the spring, and then with another peak in the autumn when the land is ploughed. In the winter farmers aren't adding fertilizers to their fields, and this impacts strongly on levels of N and K. Phosphate is a little bit different because it is mainly bound to clay minerals, so is getting into lakes and rivers with soil particle run off from arable land etc. We are losing soil at about x100 of the rate of soil creation, mainly to agricultural run-off.

In the southern UK the environment has somewhere about x3 to x10 as much nitrogen in the system as there would be naturally, relative levels of phosphate will be lower, but as a proportion of the natural background level even higher than nitrogen. It is difficult to quantify these levels, but the "best guess" estimate is that if we stopped adding phosphate to the environment tomorrow, it would take a 1000 years to deplete the reservoir back to natural levels. Nitrogen and potassium levels levels would decline much more quickly, but again we don't know how deeply the additional NO3 will permeate aquifers.

cheers Darrel
 
Thanks all, I suppose the idea is a bit hit and miss. But that's the point of EI, it keeps it stupidly simple and therefore rules out nutrient deficiencies allowing us to concentrate on CO2 flow and distribution etc.
I'll go full EI this time and start to fine tune it when I get a feel for it, the water quality data maybe of some use then...
Yep Darrel you are right, my water is principally drawn from the chalk aquifer hence the stable magnesium levels and yearly calcium levels that average 99.9mg/l...and the annual rhythm to the levels of all the other nutrients/pollutants.
Some of those figures are pretty scary though, especially soil loss.
 
I don't want to discuss the advantages or disadvantages of EI method here in particular, but I don't believe in universality. EI (or whatever other universal method) just can't be good for all plant species, and each plant has its own demands and strategies for nutrient uptake. For some plant species the optimum nutrient levels can be in different range than for others.

For example, here are some optimum values for different plant species (optimum concentration = external concentration of nutrients needed for maximal growth):
Pistia stratiotes = 19 ppm NO3, 8.9 ppm PO4
Salvinia minima = 23.5 ppm NO3, 8.9 ppm PO4
Vallisneria americana = 93 ppm NO3
Ruppia maritima = 6.8 ppm NO3, 0.2-0.4 ppm PO4, 0.08 ppm Fe
Lagarosiphon major = 3.7 ppm NO3, 0.37 ppm PO4
Elodea canadensis, Elodea nuttallii = 7.4 ppm NO3, 0.74 ppm PO4
Eichhornia crassipes = 22 ppm NO3, 1.5-3.0 ppm PO4
Callitriche cophocarpa = 19 ppm CO2
Elodea canadensis = 35 ppm CO2
Egeria najas, Egeria densa = 44 ppm CO2
Potamogeton crispus = 66 ppm CO2
Hydrilla verticillata, Ceratophyllum demersum, Myriophyllum spicatum = 22 ppm CO2
Utricularia species = 44 ppm CO2
Hydrilla verticillata = 2.4 ppm Fe
Potamogeton gramineus = 0.9 ppm Fe
Potamogeton nodosus = 5.6 ppm Fe
Potamogeton pectinatus = 8.9 ppm Fe

These data was gathered from different scientific papers. Also, be aware of the fact, that although these values are meant for an optimal (i.e. maximal) growth, for a good growth (at 70 to 90% of their maxima) plants make do with much less concentrations. For example, if for Utricularia species (true CO2 users) about 40 ppm CO2 is optimum, for 50% growth they'll need just 1-2 ppm CO2! So if you have 20 ppm CO2, your Utricularia will grow at about 90% of its maxima.

The same applies for toxicity levels (or levels where some plants begin to hinder their growth) also. For example, for Potamogeton crispus the optimal CO2 level seems to be somewhere around 60 ppm, but with Elodea densa CO2 level of 40 ppm can already cause quite dramatic inhibition of photosynthesis (growth). So with aquarium plants there's nothing like universally optimal nutrient levels. Unfortunately, no one (even T.Barr) seems to care nor do anything to find out what are the real nutritional demands of different aquarium plants. Couple of moths ago, T.Barr (with ~20 years of experiences with growing aquarium plants) said that he is working on a special Plant Database, but I doubt he will show us any usefull data like this.
 
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The complexities of the different amount,salt dosage etc are something I steer clear from,but then again I only have easy plants. John at APF states the recommended dosage is not a given that's the estimate so it works for me stems growing well above the tank if had to I needed I suppose I would increase dosage but I don't need to .I tried EI after a article by Nathan Hill. Previously used still do on one tank Neutro plus with similar results the Doc at AE swears by it and it didn't disappoint.Agree with Ian about tap water never quite the same.
 
Hi all,
Troi said:
Some of those figures are pretty scary though, especially soil loss.
Click to expand...
We've been able to get more accurate estimates of soil loss since nuclear testing and Chernobyl. There is a global background level of caesium137, from the nuclear bomb testing and then another big slug of Cs-37 from Chernobyl, and we know exactly when that caesium arrived. This is an <"easy read">.

You can see a good example of erosion on the Downs, where we've ploughed out 12,000 years of soil in the last 50 years of growing winter cereals.

cheers Darrel
 
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