Fertilization Strategies

Hi Prof

I know you are working on your new fertilizer, but if you have the time I was hoping you could read through this thread and perhaps make some comments, based on your knowledge and experience.

http://www.aquaticplantcentral.com/forumapc/algae/62516-method-controlled-imbalances-gda.html

I have been reading quite a lot of the ideas presented by Christian Rubilar, and they differ quite a bit from those proposed by Tom Barr and his EI method.

The original article by Christian is here, but in Spanish. You will need to paste this link in the google search box and then select "translate" when the results a retrieved. The translation tool leaves a lot to be desired, but after a few reads one can start to understand.

http://www.drpez.net/panel/showthread.php?t=154436

There is also a debate between Tom Barr and Christian on this thread.

http://go.aquaticplantcentral.com/?...et/panel/showthread.php?t=307546&page=2&pp=25

The most important thing I learned was that each tank is different, so one should rather try to find your tank's consumption point for each required element, instead of sticking to rigid rules. Christian feels there is no need to overdose on all the chemicals (for example the EI method). This makes sense to me especially in a tank where you want to keep fish in healthy conditions and not in a "fertilizer bath", as you called it in another thread.

The tough part is that it requires more work from the aquarist and careful consideration of each move. It is easy to just add a predetermined amount of fertilizer each week after 50% WC and then just leave the tank to do its thing until the next WC. But then the aquarist also learns something and become more involved in the intricacies of the ecosystem.

The other thing to consider is that both these guys constantly refer to CO2 and the need to keep it at around 25ppm. We have had the discussion regarding CO2 and soft water, I don't want to go into that again. More and more people are using DIY CO2 while others are now starting to use pressurized CO2. Whether the expense is justified is a matter of opinion. At this point I cannot justify it. Tom often makes mention of the problems related to CO2 being the limiting factor in a tank.

So what I am asking really is your opinion on the arguments of Christian as opposed to those of Tom, with reference to your new fertilizer which you say is based on EI.

Regards
Lauré

 

Hi Lauré,

Thanks for this thread, you always post some food for thought.

For those that do not know, yes, I am working on an addition to my Dirk's drops fertilizers, as there is so much interest in the EI method especially using a higher tech setup, especially if you use more light on your aquarium. Thanks to the cheap Chinese imports (God alone knows what they are doing to their environment and ours for that matter in the process) metal halide lamps have become affordable as a result of which plants can grow better but also need more food!

I fully agree that every aquarium is different and therefore requires a different fertilizer regime. I have now done some experimentation where I have used my basic two solution Dirk's drops ferts and then I have developed a third solution that gives you the typical EI method nitrate, potassium and phosphate mix in which the ratio of nitrate to phosphate is 10:1. Although I can see a major, major jump in the growth of most plants, I am not happy because the growth of algae has also jumped in some aquaria but not in all. Those that have a high fish load are showing algal growth, which I interpret in terms as an overfertilization of phosphate. I now want to formulate a phosphate free mix as well so that I can see if this will get the algal problem under control as it has been repeatedly said that if the phosphate to nitrate ratio is too high, algae will grow. However, in tanks with a low fish stocking ratio, I see improved plant growth but no algae, so exactly as you say, the requirements differ from one aquarium to the next. This has fairly major implications for my formulations as I may have to formulate a NK mix without P and an NPK mix. I need to experiment more to find an optimum. So, in principle, I agree with your points, it is not so simple that one can make one mix and think that it is going to work for all aquaria.

On your comment about CO2, we need to think carefully about this. The really big difference is that in Europe and the USA, just about all water is high in carbonate hardness, they simply do not even think of our conditions where we have such low carbonate hardness in areas such as Cape Town and PE. Everyone is surfing the internet at the moment and they just blindly think that they need CO2, then realize they can't afford the CO2 cylinder and controller and then go the DIY CO2 route. I still maintain that it is completely unnecessary if you have such soft water. Also, if you really want to use CO2, you MUST increase the carbonate hardness as you otherwise have these major pH swings which are really detrimental for both fish and plants. For this reason, I am also going to produce a carbonate hardness generator so that you can add carbonate hardness to the level of about 4 dKH and then you can use CO2 without all the dangers of the pH drops.

However, I remain firmly convinced that you do not need CO2. I have a very small aquarium which has Sagittaria subulata growing in it on a windowsill where it gets full sunlight. Without CO2 and WITH a corner filter in which I aerate the water, I get pearling from the leaves with the addition of all my ferts, so why bother with CO2?

Thanks for your comments, it is always a pleasure to answer a thoughtful question..

Kind regards,

Dirk

 

Hi Prof

Thank you for your inpput. Possibly for the sake of others who have not read through the links above, Christian Rubilar developed a strategy he calls "Method of Controlled Imbalance" (MCI). I would like to quote Christian:

Prof, this is exactly what you are saying you found. Some tanks with low fish load respond well to your new NPK mix, while those with high fish load probably now have excess P. If you have GSA (green spot algae) then there is excess N.

Furthermore, it is interesting to note that Christian states he grows plants for a living. During this time he found that plants like Anubias Sp. and Marsilea Sp. are high consumers of PO4, while plants like Glosso are high consumers of NO3. It is just common sense then that if you have a tank with a large Glosso carpet that you will need to dose additional NO3, more so than in a tank with a bunch of Anubias. The latter will probably do just fine if you have a decent fish load and not dose anything other than some K and a few trace elements.

Perhaps you can just explain to me this concept of PO4 in fish food. Is it in the food and leaches in the water if uneaten? I have not really looked into this aspect of PO4 "dosing", only just assumed that feeding fish provides enough PO4.

What I found in my tank is the following:

I can do a large water change and clean out any algae. All is good. Then I dose and after 2 days I get GSA (green spot algae) showing up on the glass. According to Christian:

So I clearly have a PO4 shortfall, in other words, my plants uptake PO4 pretty quickly and the next thing is an imbalance between PO4 and NO3 which results in the GSA on the glass. It is not too much trouble, because it can be wiped off with a little elbow grease. Yet I am still unhappy as I know there is a PO4 shortfall. At this point I am not dosing anything to compensate, I just keep cleaning. I also know that PO4 is involved somewhere in the uptake of carbon by the plants, so perhaps my plants are battling with that too?

It is interesting to note that Christian states that the conditions for GSA are totally different to those of any other algae. So getting GSA is a good thing. It means no other algae can multiply under those conditions.

Furthermore, all these guys work with hard water, as you mentioned, so we have to take that into account when examining their strategies.

Once again, thank you for the response and we all look forward to your new fertilzer formulas.

Regards
Lauré

 

Hi Lauré,

I have had a long day today so I will just make some brief comments.

Phosphate is not added to the water via uneaten food, but via the droppings of the fish. Most fish foods contain around 1% P by mass, particularly if they have a high protein content which invariably means it contains a lot of fish meal. Muscle tissue contains a lot of phosphate as ATP is used in muscle to supply energy for contraction and as fish meal is largely composed of muscle, this has a high P content. Thus if you keep a lot of fish in an aquarium and feed them heavily, this will result in a large amount of P getting into the water.

I hear what you are saying about P levels influencing GSA, in other words that you need ENOUGH or HIGHER levels of P to keep GSA in check. Is this not directly in conflict with Tom Barr and co who say that high P levels stimulate BGA and other types of algae. If these deductions are correct, it sounds like you cannot get out of the algae spiral. How do you understand this?

Light definitely also plays a role in GSA as areas in my tanks that have higher light are more prone to GSA than darker areas. I hear repeatedly from folks that they find that under high light they have these algal problems, but my initial NPK mixes seem to be stimulating GSA in these tanks. In those with low light, no problem. Your thoughts on this?

Kind regards,

Dirk

 

Hello All
Firstly thank you for a excellent article Prof.
In my experience the GSA need quiet large amounts of light and therefor will not grow in poorly lit tanks. Furthermor did I found if I have lots of plants which have there main nutrietion intake through the leave and stem GSA are less than in tanks with natuarly swomp plants which are mostly purly root feeders. My conclusion is that depending on the plant species, fertiliser can be added to the water or HAVE to be applied into the substrate, this especially in the case of p and F.
What is your experience in this respect as it impacts on the amount of different feeders in relation to each other in a given tank
Thank you
kind regards

 

Hi Guido,

Thanks for this article must firstly go to Lauré who started this thread. He has been doing a lot of research into this difficult field and has been coming up with some interesting findings.

One of the the things that make this field a nightmare is the lack of decent scientific experiments in which one has two tanks say that have all the treatments (light, ferts, CO2 etc) the same and then just varies one thing, say nitrate so that one can see the effect of the one variable only.

I agree that some plants need nutrition from the medium. In particular, Cryptocoryne need ferts from the medium I find. Many other plants can be fed from the water, and actually do not need substrate feeding at all. It is therefore clear to me that we cannot make general statements, a lot depends on the plants' specific needs. What gets even more complicated is if one keeps different plants together. Clearly some plants must be faster or better at absorbing nutrients than others as a result of which those plants will not do so well in combination. I actually am of the opinion that trying to combine everything in one aquarium is just about impossible so I grow many plants on their own or with a limited number of other plants.

Just one question: What were you meaning about adding F? F stands for flourine, I assume you mean Fe or iron, is that right?

And yes, high light does help algae so in these tanks it makes control even more difficult.

Kind regards,

Dirk

 

Good morning

sorry for the slip yes I did mean Fe.
To your other point of control tanks.
I had the previlage to work in a place where we had groups of 5 o more tanks with all the same conditions(Same size, same light, ONE watercicle, same temp etc ). And it was amaising and at times frustrating how different they still "performed"
I think thats what makes our hobby so interesting and versatile and lets us constantly lern.

 

Hi Prof and Guido

I am glad this thread is actually stimulating some interest from other forum members. That is the idea.

In the past the "go-to" man used to be Tom Barr for many plant enthusiasts. I have always agreed with Prof Dirk that I cannot comprehend keeping fish healthy in a "fertilizer bath" as per EI method.

I think most forum members are pretty familiar with EI, so I am going to summarize in a few paragraphs MCI, Method of Controlled Imbalance. Why? Because you work towards an imbalance which you can control. This imbalance is the Green Point, or Green Spot Algae (GSA). Christian Rubilar chose this because it does not attack plants except for some slow growing Anubias leaves when it gets bad. But the idea to not let it get bad. More about that later. The point is that at least you know where you are and what you are working with, instead of having a bunch of parameters and no consistency. Also, GSA grows in conditions not favoured by any other algae: high light, high NO3, low PO4, good CO2, good flow.

Firstly, a couple of requirements. High light, at least 3WPG, and CO2 of at least 25ppm. Then you know there is no limiting factor regarding these nutrients. The only thing you then deal with is fertilization. It has also been reported that MCI works with 2WPG by some forum members on APC and by Christian himself.

So you clean out your tank as best you can and do a very large WC to reset it. The next step is to only add KNO3 at 1g/200l daily until you reach the Green Point (GSA). You add up all the daily doses and the sum will be your weekly KNO3 dose in between water changes. Probably best to divide this into 3 equal parts, similar to EI. So now you know your tank's nitrogen consumption point. But you have GSA. You may still have other algae, but they will not be blooming under these conditions. They will die eventually and you can clean them off manually. They won't bloom.

Repeat this for a couple of weeks until you are sure about your method. Clean off the GSA manually once you get it. If your calculations are correct, it should appear on day 7 just before your WC.

How to get rid of GSA? Now you start adding PO4 at 1g/2000l daily until no more GSA. That is your tank's weekly PO4 consumption. Easy method?

I found this a little confusing and I have since engaged into some conversation with Christian over at APC. Surely fish load, as explained above, contribute to PO4? I will get more clarity from him. The way I understand it is that you have to manually try and balance the NO3 produced by your bioload and the NO3 you add to the tank with the consumption rate of your plants. This you then balance against the PO4 produced by your bioload, and possibly add PO4 if required in order to get rid of GSA as the last step. It may take a few weeks to get this right. The idea is to only add what your tank needs. It would be fantastic if your tank needs 0.3ppm PO4 daily and you add this in the morning before lights come on and when you measure after lights out the level is 0ppm. That is perfect, isn't it? Then tomorrow you do it again. However, this is not always practical, so a general balance for the entire week between water changes must be found.

When to dose other elements? Well, as soon as you have the controlled imbalance Green Point, you can slowly add a little bit of gh booster (Mg, Ca, etc) and dose your traces.

Above I quoted Christian. He asked the question: why fertilize the tank per volume of water as a generalization? Shouldn't we be looking at fertilizing the plants instead? He had a nice analogy with dinner guests, but you can also ask: do you dump food in your tank based on the water volume, or do you feed based on the needs of the fish you are keeping? Why should plants be treated differently?

Sure, fish can come to the food but the food must come to the plants. So we fix that with decent water flow. That's easy enough.

Prof Dirk, I have a few questions. Firstly, with respect to Ca and Mg. Here is part of my conversation with Christian.

I would like to hear Prof Dirk's comments on the ratio. I specifially asked Christian about this because I was concerend about Green Dust Algae (GDA) and in another thread he mentioned that after many months of experimentation he came to the conclusion that GDA is caused by a complex imbalance between Ca and PO4, but he cannot say for certain. What he could say was what worked for him in most cases.

What they are saying is that a certain level of P is required by the plants. Very little, in fact. This is a generalization, because Marsilea and Anubias are priority consumers of P and you would require more P in such a tank than in a tank with Glosso, which is a priority consumer of N. BGA is stimulated by high P vs N levels, mostly where the N is pretty much 0 for a day or 2. Tom is adament that this is the cause of BGA. He has stated on many occasions that his statements are always based on repeatable experiments, not just theory.

Christian and Tom both grow plants for a living. They both test these things repeatedly and come up with conclusions. There is not much difference in what they are saying; the philosophy is different.

Tom says let's make it easy and dump a bunch of stuff in the tank so there is never any shortage. Poor fish...

Christian says hold on - we are not feeding a volume of water, we are feeding the plants based on each tanks indiviual requirements. Much better for the fish, I'd say.

To answer the question - yes there are people with the time and resources to test these things out. Can we trust them? Good question. I am a pretty analytical person. I like to test things out for myself, but in the end, sometimes you have to go by what others are saying. I can agree with a repeatable experiment and take the outcome as the gospel. As a scientist you surely support this, Prof?

Absolutely. I want to touch here on another important aspect of MCI. The need to understand Bio-Indictors. Plants are used to judge your success, algae used to judge your failures. Do not view the algae as negative. It is used in the MCI as an indicator of where you went wrong and if you understand the method, you can fix it. This method requires a lot more knowledge from the aquarist, but isn't this why we are here? I understand the average guy wants to keep some fish and a few plants, so a commercial product dumped in the tank once a week might work. But we are on this forum because we show an interest and we want to gain knowledge and become better at what we do. Right?

Finally, please note I am not slating Tom; I just don't agree with adding tons of chemicals just to "cover your tracks". Once thing I have learned from his articles is perhaps the first thing one should ask. What is the goal? Do you want to create a beautiful aquascape and trim weekly and lots of water changes, do you want a nice display that takes little effort, or something in between? What is the goal?

Regards
Lauré

 

Laure, don't worry, these threads usually stimulate lots of interest i'm sure

Most of us usually just read them though, lol,

Think of us rest as silent partners :smile:

 

Hi Laure.
If I understand T.B's IE and Christian's MCI methods correctly,you need Co2 in ecess
of 20ppm and lighting of 2w/litre and the tank heavily planted.
So,failing in even one of these conditions,Co2,lighting or plant volume, makes using
either one of these methods fruitless or should I say useless.
I am following your conversation with Christian on the APC site and he has already
pointed out that your lighting is not sufficient and you also stated that you are not injecting any Co2.Are you goiing to remedy this and then start the MCI dosing?

 

Rudi

I am actually challenging his statement, as I don't believe my lighting is insufficient. Some people have an obsession with high light. In that same thread he admittted that MCI can work with 2WPG, and my light is 3WPG.

Actually, let me talk about that quickly. I hate referring to the WPG rule. Watts is a measure of power comsumption and not light output. We should be looking at lumens, as that is a measure of light output. But the lumen, once again, is a measure of light output as percieved by humans. Plants apparently "see" light differently and have affinity for certain spectra, like red and blue, while humans see green the brightest.

My opinion on this matter is that you should actually forget about red and blue spectra, as red light gets filtered out by water pretty quickly. What you need is light that makes the tank look good to you and then it must also be strong enough accross most wavelengths. I found no evidence of any particular wavelength being better than the other for aquatic plants. All the tests you read about where they present scientific data are for terrestrial plants. In nature, these aquatic plants grow in streams shaded by tall trees in tropical forests, so the light is at best fairly filtered.

Getting back to your question - I have challenged his statement regarding my light as I have 20300 lumens over a 150 x 45 surface area and the depth from surface to top of substrate is 47cm. I think my plant growth is pretty good. In fact, the light is too strong for Limnophila as it is growing out leggy. Have a look at my tank thread on this forum.

CO2 is another matter altogether. I think my CO2 is adequate. It can certainly be improved by injecting CO2, but I cannot afford and justify that expense right now.

Making use of EI in failing any of the conditions you mentioned will probably result in disaster. As stated above, I think dosing in excess is not my personal preference. I can only see problems. Some of the ratios are also questionable.

Using MCI is probably going to work. Why? Because you are actually finding out at the beginning how much your tank is consuming, and then you dose that. So your dosage will differ depending on how heavily you are planted, which species you have and how much light you have. Higher light drives plant growth, which in turn drives nutrient and CO2 uptake.

Does this make sense?

Regards
Lauré

 

Just a question.

Seeing as you are dosing, or planning to dose for your plant-content specific needs with MCI, would you have to remeasure the greenpoint with every new addition or subtraction of your plants?

In other words, everytime you rescape and add plants, or decide to scale down a bit, or remove one big plant, like you are planning with your main display tank laure, then the plant content changes, and so the consumption point will change, and having to retest continuously for a few weeks every time might become a bit tedious right?

No doubt the MCI method is better than an OD of EI dosing, but still, hard to implement for an average hobbyist, this seems the way to go for hardcore plant enthusiasts rather than your Everyman..

 

I am sure colour tempratrure and Kelvin play a more important part.
Although a full spectrum light will get your plant to grow, but thats wasteful in my opinion.

 

If you like we can start a thread on lights, but let's keep this one to the topic. :smile1:

I'd be happy to explain in detail my statement above.

 

I've followed this thread since it's "inaugoration" and I must admit... it has been ver interesting.

I second Ferryman's question... because you will be finding the ideal dosing according to MCI method on NO3 and PO4 based on that exact tank set up... i.e number of plant and number of fish. BUT what happens in 2 weeks time when the plants have doubled in size, and in 4 weeks time when you have introduced new fish, and/or lost fish and/or fish have grown. Surely that need to become part of the equation somewhere?

 

Exactly. Remeber, I am not saying here that MCI is the ultimate answer. I am just saying that I agree with the philosophy of targeting plants instead of water volumes. But I do believe this question was answered in the thread on APC.

Hi

Yes I made the point that the "Everyman" can go and buy a commercial product and dump it in his tank and acheive some plant growth. Possibly a while later there's algae, but then he goes and buys a product to fix that and all is happy again (for a while until the next problem). Tanks don't need to be a science, you can just go ahead and spend money on each problem or requirement and enjoy it. Some people find that very satisfactory. They also don't have the time or even the interest to delve deeper.

What I said about Tom Barr was that the most important thing I learned was the question: "What is the goal?"

That question is more important than you think. It needs a bit of consideration and then you make a decision on how to approach your tank based on your answer. There are methods that fit every answer and they are all easy within context. Your tank WILL be a success and you WILL gain satisfaction from your hobby. The issue is when you implement the wrong method for the goal. That is when the frustration can get the better of you and people give up on the hobby.

 

You pose a very interesting topic Laure, and I would be very interested in following your thread.

My question would be, can you BUY PO4 and NO3 off the shelf to add to tank? I mean buy pure PO4 and NO3 without all the other fertilizer junk that comes with it?

I've always worked on the principal that the moment I see algea, I generally manage to concur it by ADDING fertz for the plants... thus increase the plant growth, decreasing the algae growth. Not sure how correct the science works here, but seems to work in general. But I never really have bad algae that needs any major concern or work anyway.

 

My idea here is to get Prof's input on some interesting philosophies and I am also glad that some other forum members have taken an interest to this topic. That is the reason why I posted this as a thread and not a PM to Prof Dirk.

No you can't. But both come with potassium which is also important: KNO3 and KH2PO4.

This is important, but for reasons other than what seem obvious here. What you are doing is using algae as a bio-indicator in your tank and it is telling you that there is some imbalance. You fix this then by correcting the fertilizers.

 

But from what I understand from this thread is that by adding fertz when the algae shows up... I fix that imbalance... THEORETICALLY.
Am I not correct in saying that the imbalance could be an imbalance of only 1 or 2 elements that are short, and in throwing in a (multi-purpose) fertilizer, I could be overdosing the rest of the elements that aren't necessarily needed? And thus creating a fertilizer bath for my fish.

 

Zoom, you are getting it! :idea:

Welcome to the revolution! :blink1:

We really have 2 options: dose invidual elements, or dose a pre-mixed solution. Option A requires more skill, while Option B can never be totally acurate.

Option B is still the preference of many, so the trick is probably to get it formulated so you are in the ball-park without causing any obvious issues.