Dry ferts - please help me with the maths

[ghostsword]

Well, one of the reasons is that plants have two basic categories of nutrient uptake. A low affinity system, which does not grab the nutrient molecules as eagerly, and a high affinity system, which aggressively attracts the nutrient molecules.



So what happens is that when you dose high amounts infrequently, the nutrient availability skyrockets initially, growth increases quickly and the plant drops production of the high affinity system components. The plant calibrates it's systems to the high nutrient load. Then, later in the week, when the nutrient values decline, the calibration becomes invalidated. There plant now has more mass and expects to have the high nutrient load, but it is no longer present. Nutrient uptake rates decline and the plant then tries to engage the high affinity system.

All of these changes takes time. They don't happen overnight. So the plant is trapped in a continuous loop of switching from low affinity to high affinity while uptake rates suffer at some point in the loop. Over time this reduces their efficiency, and generally their health will suffer. Again, this does not mean that it will always happen, or that it always will be terrible. This is just a general pattern.

Cheers,

Been a member of the forum for a while now, and have read and discussed many things, but this is new to me.. 🙂 and absolutely makes sense. I knew the plants take about two weeks to adapt to a change in dosing, but did not knew why.. now I know.. 🙂

 

[wet]

I just wanted to restate it: so why over dose when you don't have to, especially if you don't want to maximize yield/growth, and the gardener intuitively feels safer limiting levels in their tanks? *That's still EI if you want to argue about it* 🙂

 

[wet]

Also, another point: Plantbrain often suggests ramping down on dosing (start high, then back off). I actually prefer this way as well on a new tank with no fish (because I do not add fish until my plants are growing and therefore uptake nutrients), but I think your plan of going up will work fine, daizeUK, especially going off some of your goals in the CO2 thread and easier plants to start.

 

[ceg4048]

I just wanted to restate it: so why over dose when you don't have to, especially if you don't want to maximize yield/growth, and the gardener intuitively feels safer limiting levels in their tanks? *That's still EI if you want to argue about it* 🙂

That's your own personal paranoid intuition. Not that of EI, which does not address feeling "safer".

If you don't want to overdose then don't overdose. The point is that you don't have to be paranoid about dosing inorganic nutrients.You are making arbitrary and unqualified assessment of the effects on fish health and yet you have no data to show. We collectively have empirical data to show that there are no ill effects at the levels we dose. The toxic levels are orders of magnitude higher. The same cannot be said of CO2 or gluteraldehyde, or even fish food (since most people kill their fish by overfeeding). So it doesn't matter which recipe is used. Fish consistently breed in EI dosed tanks and they live as long or longer than fish in un-planted tanks.

So what we've shown is that if you want to lower the dosing you can, and if you want to increase, you can. You are not restricted in any way to any recipe or spreadsheet. This is an old argument. We've specifically dosed higher levels in order to show that there are no toxic effect of NO3 and PO4 at the levels we dose. There are plenty of studies out there on the toxic effects of NO3 for example:
Studies on the toxicity of ammonia, nitrate and their mixtures to guppy fry
There are other studies using guppy fry which show the NO3 toxicity (without ammonia) at over 700ppm. These are ridiculously high numbers that we never approach.

There are occasions where the so-called capped levels still result in deficiency. This is normally due to poor flow/distribution. The flow should be fixed, but oftentimes the hobbyist may lack the resources to accomplish that. A dosing increase can improve the situation in that case. The fact that we have been dosing standard levels, as well as higher values for years without any negative effects means that you can use any recipe you want and not quibble over a few ppm here and there. We've specifically pushed the limits in order to show that there are no ill effects.

In fact, it seems to me that you are contributing to the nutrient paranoia, and that your spreadsheet is presented as some kind of knight in shining armor protecting the world against overdosing. Meanwhile, in the real world, we can delete the spreadsheet and dose what we want without any care or worry. A TDS increase is the only penalty with eutrophic dosing.

EI dosing also means that you can lower the dosing values if you want to control the TDS or if you want to limit the water changes and maintenance. You can go in either direction without fear.

So that's why it doesn't matter which recipe you use and why few people care about spreadsheet numbers. There is no point becoming mesmerized with Spreadsheet cells and formulas. Just grab you teaspoon and get on with it. That's the whole point of EI, simplicity. No spreadsheets, no formulas, no ratios, no worries. The only other penalty of overdosing is wasted salts, but that's an economic issue.

I reiterate that there are plenty of things to worry about in a CO2 injected tank. Dosing is not one of them. Arguing about 1ppm versus 3ppm is patently absurd. Pick a recipe and follow it. Observe the plant's response, then make adjustments from there, based on real objectives, NOT based on paranoia.

Cheers,

 

[daizeUK]

Thanks very much for your answer Clive!

There are plenty of studies out there on the toxic effects of NO3 for example: Studies on the toxicity of ammonia, nitrate and their mixtures to guppy fry

This study is giving figures for the death rate after 72 hours at extremely high levels of exposure. This is not particularly relevant to EI unless we're going completely mad with overdosing so I am more interested in studies which look at the long-term effects of moderate nitrate levels, e.g. Nitrate toxicity to aquatic animals: a review with new data for freshwater invertebrates . This indicates that there are species of invertebrate and fish that should not be subjected to long-term exposure of the sort of nitrate levels that would be achieved with moderate EI overdosing.

Are you sure that EI can be used and overdosed as needed when there are sensitive species of shrimp in the tank?

So that's why it doesn't matter which recipe you use and why few people care about spreadsheet numbers. There is no point becoming mesmerized with Spreadsheet cells and formulas. Just grab you teaspoon and get on with it. That's the whole point of EI, simplicity. No spreadsheets, no formulas, no ratios, no worries.

Humour me for a moment, since these spreadsheets exist then I'd like to understand where they are getting their numbers from! 🙂
I understand Wet's spreadsheet because it's clearly based on Tom's EI target values which in turn are based on his empirical values for maximised plant growth. I can take these values as a guide and adjust them to my personal circumstances, for example increasing them if my flow is not perfect. Why would a spreadsheet (or any other dosing guide) recommend higher values than these to begin with? I'm just curious in case there is some ambiguity over the maximum phosphate levels than can be utilized by plants?

I suspect I may need to ask TNC directly to get the answer to this 🙂 but their spreadsheet seems to be out of action now.

 

[ghostsword]

I just dose EI according to the one mixture that Clive posted a few years ago. I do not measure amnomia, nitrates, ph, do not test for any of that.

Only thing I do is dose lots (it is cheap), do two 50% WC a week, with 25% RO mixed in (as London water is very rocky) and that is it.. Simple..

Complicated is lights, flow and co2, that I need to spend time adjusting and getting just right for the scape in the tank.

 

[daizeUK]

Thanks Ghostsword but I am not debating whether EI is simple to use.

I don't need to know how the sun works in order to live. The sun keeps me warm, it doesn't matter that it is a superheated ball of hydrogen and helium gas or that the surface temperature is 6000°C or that one day it will burn through its fuel and turn into a white dwarf. The sun shines, it's that simple and I don't need to know anything else. I just like knowing 🙂

 

[ghostsword]

Maybe I misunderstood the post.. 🙂

You want to know the maths to something that is as varied as anything in nature?

I do not think that there is a mathematical formula that applies to all tanks and layouts. The fert companies would like us to think so, but no two tanks are the same, and a tank today is not the same tank next month.

How can you measure the uptake of 10 plants in a tank, where the flow, co2 and light does not often grow exponentially with the plant growth, which in itself is dependent on the ferts you dose?

So easier to dose above the level you may think you need, and hope that is enough, allowing to manage the areas you can such as light, Co2 and flow.

 

[ghostsword]

The spreadsheets are there as a comfort zone, as a guide, but in real life unless you know what you got on your tank, and experience on your side, you will more often than not make a judgement error, and either dose too much or dose too little.

That is why aquascaping is more than putting rocks and wood in the right place, it is a balancing act and I believe that with every scape, every plant choice, every trimming, you are moving the goal posts and much adapt your technique to it.

 

[daizeUK]

I believe you're absolutely right but as you said, judging that balance is down to experience and I'm not at that stage yet! As a beginner I have to choose a starting formula and this is purely a question of scientific curiosity to understand what I'm choosing. I want to know where the spreadsheets get their numbers from. I know Clive keeps saying it makes no difference and I am not going to argue with his infinite experience in that regard but whether it matters or not, enquiring minds still want to know! 😉

So my question remains, why are certain spreadsheets recommending higher doses than Tom Barr's maximum capped limits?

I can totally understand if a person advises me to dose at 3x EI. I could ask you, Ghostsword, and you might make a rough judgement based on my plant mass and flow rate and lighting levels and you might personally recommend that I start dosing at 3x EI. However spreadsheets are based on formulas and they don't usually pick arbitrary numbers out of the air, so there must be a reason for it to do that.

I realise I'm not likely to get a specific answer unless I ask the authors of the spreadsheet, hence the more general question - is there any ambiguity or controversy regarding Tom Barr's maximum EI levels that would explain the different targets between spreadsheets?

 

[ghostsword]

I think the best is to ask the authors.. 🙂

I started with Clive's formula for EI, which is based on a ppm of ferts in a tank when dosed daily, then I tweaked for the results I was getting, as my tap water also had an impact.

Now I am in Cape Town, so surely I need to tweak again for the results I need, as the tap water composition is different from the one in London.

This was the article I used:
The Estimative Index (EI) Dosing with Dry Salts | UK Aquatic Plant Society
"
At this unlimited lighting we can then measure the uptake rates of the various nutrients. Since adding more light did not result in any higher uptake of these nutrients, the uptake rates measured under the unlimited lighting can also be considered to be unlimited nutrient uptake. On a weekly basis, these measurements were recorded to be the approximate values:
Nitrate (NO3) 20ppm per week
Potassium (K) 30ppm per week
Phosphate (PO4) 3ppm per week
Magnesium (Mg) 10ppm per week
Iron (Fe) 0.5ppm per week"


So there was a set of tests before those values were pulled out.

I used that as a base for my own tanks.

 

[roadmaster]

Have you asked the author's?
I have seen formula's all over the place.Some take into account source water content,some are tailored for low tech,Non CO2, Some suggest no Pottasium due to that found in KNO3,KH2PO4.
Some suggest Equilibrium,GH booster for softer water. (Mg)
I think that's the appeal for some/many.You can start with non limiting amount and work down/up according to each application.
But I should ask the author's were it me.(I did)

 

[ceg4048]

This study is giving figures for the death rate after 72 hours at extremely high levels of exposure. This is not particularly relevant to EI unless we're going completely mad with overdosing so I am more interested in studies which look at the long-term effects of moderate nitrate levels, e.g. Nitrate toxicity to aquatic animals: a review with new data for freshwater invertebrates . This indicates that there are species of invertebrate and fish that should not be subjected to long-term exposure of the sort of nitrate levels that would be achieved with moderate EI overdosing.

Yes, those data are for temperate waterways, not for tropical species. Also important to note is that they are not reporting the NO3 concentration level. They are reporting the "N" portion of the NO3. So because of the ratio of the weight of N to the entire molecule you have to multiply the N-NO3 value by 4.42 in order to get the NO3 concentration level.

So nitrate above 44ppm may be a problem if you are keeping rainbow trout or salmon, but that has nothing to do with tropicals.
Again, we've collectively been dumping these powders in tanks for years. No long term effects have been noted. Plants grow well and that helps the fish, because Oxygen is more important than anything else.

Why would a spreadsheet (or any other dosing guide) recommend higher values than these to begin with? I'm just curious in case there is some ambiguity over the maximum phosphate levels than can be utilized by plants?

Well, I predict that you'll not get any good answers because nobody has tried to figure out maximum uptake of PO4. Folks just use the most popular recipes, ones that they know work and that they know they can suggest without any issues. As I mentioned, we've already demonstrated that there aren't any ill effects of high NO3, PO4, Fe content.

Cheers,

 

[daizeUK]

Well, I predict that you'll not get any good answers because nobody has tried to figure out maximum uptake of PO4.

Did Tom Barr not do this? I thought he worked out the maximum uptake of all nutrients and that's where we get the 3ppm from?
Forgive me, I've been trying to find the link to his research all evening and I must be blind but my Google skills are failing me tonight

 

[ceg4048]

It's unclear whether he directly measured uptake rates or whether he measured growth rates. Precise determination of uptake rate is extremely difficult. Growth rates are much easier to determine by measuring the dry weight. When growth rates don't improve with increased dosing then there is no point in dosing more. That's how he arrived at the baseline numbers. But he never cautioned against exceeding these values. He simply stated that using higher values was a waste of money due to negligible gain. His baseline numbers have nothing to do with toxic effects.

As Luis and others have pointed out, and what I've tried to explain, is that each tank is a little different and in Tom's test tank(s), his flow/distribution was good so he didn't notice any changes with additional nutrient loads. In larger tanks with poor flow however, it can occur that higher nutrient loads have an effect. Since there are no known toxic levels of PO4, a few ppm differences is not something worth worrying about.

In any case, whether you are concerned about toxicity or of being accurate, or both, we can tell you without reservation that:
1. Being accurate will not improve performance at all.
2. Other than higher TDS, there are no short term or long term negative impact of higher PO4.
3. In some cases, higher nutrient levels than baseline can show improvements in plant health.

We didn't just dream these conclusions up. It's based on what we observe in our tanks collectively, for around 10 years (including PMDD dosing strategy), as well as what we note in the scientific journals - as well as information directly provided by Tom Barr.

Higher nutrient loads typically result in higher levels of organic waste, and so this drives the need for higher maintenance, such as water changes. That's a good enough reason to use lower numbers. We're not necessarily advocating higher numbers just for higher numbers' sake. What we're saying is that there are no toxicity issues, and that sometimes, when troubleshooting poor performance, increasing the nutrient loading is a useful tool for isolating the fault. Since we never have to worry about toxicity we are free to increase or decrease as required to isolate the fault. So I, at least, specifically set out to dose much higher values in order to test this idea and to see where the limits are. It's easy to kill fish with CO2 or overfeeding, but it's very difficult to kill them or even to make them uncomfortable with KNO3, KH2PO4 or Trace mix. I and many others had fish breeding in EI dosed tanks. I've raised two successive generations of A. cacatuoides in an EI tank, so there are no long term effects of these salts at the dosing levels we are using.

Cheers,