Effects of micronutrient fertilisation alone

[Spider Pig]

What would be the effect of using only additional micronutrient fertiliser in a 2 wpg tank with co2 (30ppm), N/P/K being provided by fish waste?

Would all the plants grow until the NPK is a limiting factor or would this imbalance suit algae disproportionately leading to problem algae?

Asking because planning to add co2 then maybe upping lighting later. However ideally avoid additional macronutrients unless necessary.

 

[ceg4048]

Hi,
CO2 drives the photosynthetic process. Therefore adding CO2 increases the macronutrient uptake demand because the chemicals produced during photosynthesis are mostly Nitrogen and Phosphate based enzymes. It is impossible to predetermine if you have enough macronutrient production solely from fish waste/feeding alone. I suppose if your tap is high in nitrates and phosphates, if you have a high loading and if you feed frequently you may have enough. Potassium might be an issue as well since there are not that many sources in foodstuffs. You'll just have to try it but be prepared to add macros.

If you add CO2 and you don't have sufficient NPK to match the new uptake demand you could easily fall into N or P limitation and cause algae. I have no idea why you would want to "avoid" adding macro, yet you have no objection to adding trace element. That's like saying you have no objection to taking vitamins but you want to avoid eating meat/poultry/seafood.

Cheers,

 

[Spider Pig]

main reluctance for adding macronutrients is the potential risk to the fish, as I thought that higher nitrate is detrimental to fish. However have read tom barrs article rebutting this so less worried and more ready to top up, however ideally without 50% weekly water changes- have to do more research on that side of things.

Why does the algae proliferate if there is no nitrate or phosphate for it to use, assuming the higher plants have used it first?

 

[ceg4048]

main reluctance for adding macronutrients is the potential risk to the fish, as I thought that higher nitrate is detrimental to fish. However have read tom barrs article rebutting this so less worried and more ready to top up, however ideally without 50% weekly water changes- have to do more research on that side of things.

Why does the algae proliferate if there is no nitrate or phosphate for it to use, assuming the higher plants have used it first?

Hi,
Yes you'll find that fish don't care about nitrates as much as the ammonia that it starts off as. Nitrate gets a bad rap and is blamed for everything merely because it is the end product of a chain of toxic events. Ironically nitrate production is natures method of detoxification in a water system.

Algae doesn't care one way or another about nitrate or phosphate. They use very small quantities when compared to plants. NH4 is a highly effective source of Nitrogen and so algae have "learned" to use it's presence as a trigger for blooming. The presence of ammonia usually means decay and that there will be more nutrients available. When anything dies in this world or ammonia is one of the first product. Ammonia is also the result of animal metabolism. The stench of carrion or the choking odors due to perspiration, urine or feces is caused in large part by their ammonia content. When plants are starved of nitrate and phosphate their cellular structure decomposes and the result is ejection of ammonia and nutrients into the water column. Algae sense the ammonia and attach to the plants where they find a ready source of ammonia and nutrients. When nitrates and phosphates are abundant and if the plants are healthy then they help to remove ammonia from the water column and thus help to suppress the ammonia trigger that causes the algal bloom. Therefore healthy plants, fed with unlimited nutrients and CO2 create an environment that is hostile to algae and the algae go into a form of hibernation awaiting the next ammonia trigger.

Cheers,

 

[Spider Pig]

Will a plant itself with low NPK but with sufficient co2, light, and micronutrients grow healthily? If a plant acclimatises to a low npk environment, then surely you would not get the decomposition, as the growth would slow to accomodate the amount available. As I understand it higher plants use ammonia preferentially and so any released by fish waste would be used by them, therefore not triggering an algae bloom. I'm sure this is overly simplistic but A-level biology was a long time ago.

 

[ceg4048]

Hi,
Your hypothesis is valid, except the critical component that will determine success or failure is the intensity of the light. The process you describe is valid for a low tech (low light) tank wherein growth is attenuated due to NPK limitation but health is maintained due to carbon availability. At about 1.5 watts per gallon (or thereabouts) the uptake demand for nutrients is not severe, however, as the light intensity increases beyond this level the plant cannot keep up with the demands required by photosynthesis in an NPK limited environment.

Ammonia is not necessarily used preferentially when there is the presence of nitrate (NO3). At very high ammonia concentrations NH4 is preferred. The concentration level at which NH4 is preferred is at toxic levels to fauna. At normal NH4 levels seen in our tanks NO3 is preferred. This does not mean that NH4 uptake is stopped, far from it, but NO3 is preferred. When a new tank is being cycled, the NH4 concentration are inordinately high as you well know. Plants then do uptake NH4 preferentially. This is why the "fishless cycling" works so well with plants. As the concentration drops, much of the NH4 is consumed by bacteria and is converted to NO3. The plants then use both, but uptake NO3 preferentially.

There is an interesting paradox with ammonia in that it is extremely toxic to plants. There are special areas in the plant tissues where NH4 is stored but the plant limits the internal concentration values due to toxicity. The advantage to the plant of using NH4 is that it has a much higher Nitrogen value compared to NO3. Additionally, stripping the N from NH4 is much easier and requires less energy than stripping N from NO3. In fact NO3 is actually converted to NH4 within reaction chambers first, then stripped of it's N. The limiting factor is the NH4 toxicity. Therefore NO3 storage is easier to regulate, to distribute and is not hazardous to the tissues.

In a low light tank NH4 does not trigger algal blooms very easily. There is enough time for the plants to uptake NH4 and to use it. At high light intensities the situation deteriorates rapidly. Algae spores immediately sense the presence of the light and NH4 and can respond within seconds. Dosing NPK keeps the plant healthy enough to uptake NH4 (as well as NO3). If the NPK levels are satisfactory the plants also oxygenate the water column and supports the nitrifying bacteria which also consume NH4 and convert to NO3. Therefore in a high light tank NPK + CO2 dosing is critical to the systems ability to reduce NH4 concentrations in order to keep it away from the algal spores and to in effect, suppress the algal trigger mechanism.

Hope this clarifies.

Cheers,

 

[Themuleous]

You never fail to educate Clive, fascinating stuff.

Sam

 

[Spider Pig]

Thanks for that, certainly clarifies a few misconceptions I had. Will have to pick up a good plant biology book up some time.

What I am hoping to do is be able to grow a range of healthy plants, but not require the intensive dosing regimes of EI. I plan to start co2 first and then later up my lighting from 1 wpg up to about 1.9. I see I'll need to add NPK when I do that. Is there an alternative dosing regime to EI to accomodate this that you know of?

 

[ceg4048]

Thanks for that, certainly clarifies a few misconceptions I had. Will have to pick up a good plant biology book up some time.

What I am hoping to do is be able to grow a range of healthy plants, but not require the intensive dosing regimes of EI. I plan to start co2 first and then later up my lighting from 1 wpg up to about 1.9. I see I'll need to add NPK when I do that. Is there an alternative dosing regime to EI to accomodate this that you know of?

Sure, JamesC discusses a couple alternatives here=> http://www.theplantedtank.co.uk/dosing-methods.htm
The PMDD method was used for a long time. The main feature of PMDD was that it restricts application of PO4 under the false impression that algae are supressed by limiting PO4. Barr discovered that this was not valid and that algal blooms can be triggered with PO4 concentrations of less than about 3 parts per billion (3ppb) which is a thousand times less that what we see in our tanks. PMDD has now been modified to be known as PMDD+PO4. EI is a derivative of the PMDD+PO4 concept.

You also have the "All-in-one" solution of using Tropica Plant Nutrition+. I believe there is a recent thread somewhere around here regarding typical dosing schemes using this product. viewtopic.php?f=11&t=1386

There is also a lean dosing scheme called PPS which attempts to dose just enough of what the plants consume.

Each of the dosing schemes have a different priority, therefore you need to determine what your priority is and address that priority via the appropriate scheme. If you want ease of dosing without the need to control individual components, the All-in-one scheme is for you, but the product is relatively expensive as the tank size increases. If you want to limit growth rates then the PPS or the PMDD style schemes are for you but the risk of starvation are high and PPS requires constant monitoring via test kits to determine concentration levels. This is an advanced strategy. If you want to be free of testing/monitoring (and if you are a cheapskate or are on a budget) and if you want maximum growth rates with lower risks of algae then the unlimited dosing scheme of EI is for you (see viewtopic.php?f=34&t=1211)

I'm an advocate of EI so I'm completely biased in this direction. I never understand why others feel it is restrictive or dogmatic. All other dosing schemes effectively put plants "on a diet" while EI allows plants to eat as much as they want. I find it the most liberal, most flexible, easiest and cheapest method, however any of these schemes, including EI can result in disaster if misunderstood or applied ineptly, therefore you should study carefully the concepts and methodology of the scheme you select. Unfortunately, there are no foolproof dosing schemes because fools...are ingenious. 😀

Cheers,

 

[plantbrain]

The restrictive feeling comes from the idea that Paul and Kevin, Dupla etc must have been right all along.
Having the underlying paradigm tossed out bothered many.

Some sought to meet the idea half way, suggesting that nutrients still sort of limit things, but never addressing the rest of their model 🙄

Some "balance of nutrients" caused algae to go away, but that too fell apart.
Fe excess caused algae, that was easy to show to be incorrect, then K+, then NO3........

Rather than answering such basic basal question(which I hounded them about), I got a lot of smack talk, personal garbage etc. Did not make me many friends, but this is not about making friends. I can trust a friend who says well, maybe that was not right and here's why........and does not take it personal.
Flame wars are not the goal.

Additionally, some came back claiming now it was NO3 that was the problem, and that is was toxic to fish etc.
So I did test and some research to show that was wrong for a wide range of plants and fish, shrimp etc.
Some claimed K+ was bad, or that excess Fe caused algae.

Many folks spent a lot of time trying to attack what I said, but never did any real test to see if they where right.
And that is why I got a lot more right about things than many have in the past.

Lately, the thing some enjoy saying, is that EI causes plants to grow too fast for their aquascaping desires/goals.
Instead of using common sense based on plant science, plant growth, they go after the nutrients once again.

I've never understood how so many could be so fixated on nutrients.
This has been true for the entire time I've discussed aquatic plants(15+ years).
I guess it's the only thing they can really test.



I suggest using less light to do this. It's far far more stable and easy to control to regulate plant growth.
It places less demand so you can use less ppm's of N, P, CO2 etc and makes good sense to use that approach than mere nutrients alone. but then they cry claiming they must have really high light in conjunction with low nutrients to get their colors they want from their red plants.

Oddly, I have no trouble without the lean nutrients myself.
There are many wind bags whining and huffing, but few really doing much to understand plants.
Few try to do anything outside their area they happen to fall into and get a more global view about aquatic plant growth.

Many critics and very very few problem solvers.
EI can be reduced and done daily if desired.
But the critics seldom suggest this, claiming something entirely new is "required".

PMDD and EI are not different as stated, I just suggested adding more PO4, then suggested doing away with test kits as many do not use them, they are horrid in their accuracy(at least the ones most folks buy) and most do not use them correctly anyway.

So EI is really just a notion to justify not using test kits and dosing non limiting amounts.

Then you can test and monitor things like Light, CO2..........accurately and closely without interference from nutrients.
You cannot do that using limiting methods.

If you lack the control to isolate and test something, you really cannot say much, but some cannot help but try and make conclusions based on exactly that type of logic 😡

Regards,
Tom Barr

 

[Spider Pig]

Ideally I would like to keep light levels down so that growth rates are down, but as I understand it certain plants won't tolerate this even if they are given adequate co2 and nutrition. Essentially I would be happy with a low light low tech tank but with a wider range of plants available to use. Not too fussed about red plants, thinking about stuff like riccia- just to give the flexibility in the future in creating aquascapes.

Ceg gave the level of 1.5wpg over which NPK becomes an issue. At the moment have about 1 wpg (50w/ 180L) Was considering upping by 36w so just under 1.9wpg. Would I be able to get away as a low light set up like this with a small amount of additional NPK or have to go the whole way. I'll have to research the different fertilising methods but I assume you can tweek them to meet your needs with less macronutrients and water changes?

Thanks for all the info by the way. One of the big problems in this hobby is finding true information. When I get the time I will definately have to sit down with a good book on plant biology. Can't be too much different from humans can they?

 

[ceg4048]

Hi Spider,
The wpg rule is just a rule of thumb. Lighting is extremely complicated so there is no way to predict whether, in your particular tank, X additional wattage will absolutely drive you over the limit. There is no way to predict exactly what plant will do well. You'll just have to try it. Normally, if there is sufficient CO2 the need for very high lighting is somewhat mitigated so that even the so-called high light plants grow - just not as fast. In the tropical rainforests of the world most plants are shaded by the forest canopy, or are in less than sparkling water so they are actually low light plants as they adjust to the lighting level of their environment. They can't look as spectacular as they do when grown in a hight tech environment but given the right parameters they can do OK. Many red plants simply turn green in lower lighting. They must change their pigment configuration to comply with the spectral environment. Again, you'll just have to try it and be prepared to make adjustments.

Cheers,

 

[Spider Pig]

Understand about the lighting and the generalities of the rule. As long as a high light plant will grow healthily, albeit slower, I don't really mind. There does seem to be a lot of guess work in this- bit of trial and error will be fun.

Flicking through the Tropica catalogue and picking out a selection of lower light plants but some of the high light ones look quite good.