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Spezial N - Nitrogen Fertilizer


I do not start with high lightning. Normally with 6-8 hours and 50% or less of my wattage.

I start all my tanks as densly planted as possible regarding the layout. I do alot of water changes in the first weeks. I put in a lot of shrimp very fast to combat upcoming algae (red cherry shrimp, amano shrimp).

I do not stock my filters with biofilter media. I only use filter foam in my filter. Or better said..., the normal JBL filter media.

Best regards
hi tobi, are you developing an all in one?

i was dosing your ferts

spezial n

2pumps of each per day on a 25l....do you think this is overkill? just seemed alot of people over here are dosing 1pump per 10liters of tank water.

your site is brilliant by the way, i find myself browsing the glassware all the time haha.

an All in one is in testing... but it will take some months till it will be ready.

The normal dosing instrauctions of those ferts recommend less dosing, but when your tank is doing fine => dose as you wish 😉.
You are addin from each fertilizer at the moment:

Aqua Rebell Makro Spezial N:

3,2 ppm NO3
0,4 ppm Urea (=> 0,82 ppm NO3)
0,13 ppm Mg
0,4 ppm Ca
0,8 ppm K+

Aqua Rebell Makro Basic NPK:

2 ppm NO3
0,2 ppm PO4
0,2 ppm Mg
3 ppm K

Aqua Rebell Mikro Spezial Flowgrow:

0,24 ppm K+
0,328 ppm Fe

So you are dosing in excess. 1 pump per 10 liter is far far to much.

At the moment you already add all together:

~6 ppm NO3
0,2 ppm PO4 (very lean compared to the NO3)
~4 ppm K+
~0,4 ppm Mg
~0,4 ppm Ca
0,328 ppm Fe

that's real excess... I would dose a little bit less. I recommend normally 1 ml per 50 litre of each fert. Only the NPK is dosed with 2 ml per 50 litre. Of course this is a conservative recommandation. I for example add around 2-4 ppm NO3 into my tanks daily.

I hope you do big waterchanges once a week. Especially the guys with 1 pump per 10 litre.

Maybe this can help: Nutrient-Calculator
Here you can fiddle out how much you are adding regarding many ferts. I will add a multilanguage version in some weeks... so stay tuned.
But it's easy to use: Just add under "Volumen" your tank volume. Chosse the fert to add and below "Menge" (amount) you tell the calculator how much you like to add from the fert, for example "2" ml. After that click on "Berechnen" (calculate) and you will get the amount of nutrients you are adding to your tank.

All Aqua Rebell ferts are in that calculator and many more.

Best regards
Hi Tobi thanks for the response

I did have good growth 🙂 yes very big waterchange haha

Cheers mate
I measured about a max sustained uptake of 4 ppm of NO3 per day.
NH4: about 0.8ppm per day.

Pulse uptake rates where up to 8-9ppm of NO3 per day.
NH4 remained unchanged in the pulse experiments. Likely limited by Nitrate reductase.

More biomass, closer to the lights = more CO2 demand more nutrient demand and more biomass= less mixing/dispersion. Getting that right is not easy if you wish to add just barely enough, better to add a little more.
I think in some cases, more than above rates are possible, but unlikely in 99% of aquariums.
Hi Guys

I have been reading these posts with utmost interests (like everybody here).. There are a few points I keep on wondering though, perhaps they are wrong (incomplete??) observations and deductions from the posts:

1. Is it correct that people who have dosed individual chemicals with separate combinations/concentrations have observed less growth/plant health than those who dose the Spezial N fert, plus phosphates, K+ etc separately. Or in more better language: that putting Spezial N shows much more greener growth than when done in other chemical-combinations. (Well, at least to the converts anyway 😉 ).

2. What could be implied about the synergetics in this all. e.g. does it matter when (dosing frequency, days of Spezial N & micros feeding, etc) which ferts are added to the tank. In a GH booster for example, one typically increases the alkalinity AND the hardness both at same time. Usually since Ca & Mg are the only 2 contributors to the hardness, GH and Alkalinity go hand in hand. But they are different in principle. Plus adding KNO3 salt alone would increase the salinity/conductivity, but adding the other Ca(NO3)2 or Mg(NO3)2 would also tend to increase the hardness (NOT alkalinity). How do these relative differences in salinity, conductivity, hardness, etc affect the WATER AND nutrient ions exchange accross the plant cell boundaries? Or also affect the ion-dumping from water column to the ground & thereby the CEC of the soil/gravel?

3. Even though all salts in the list are ionic (by definition), in water do they have different strength weak bonds that affect the cellular level absorption of anions (NO3 -) in presence of the cations K+ or Ca++/Mg++. Chemically does it matter to the leaf, and if so, how much. Does it depend on the plant-type it it absorbs certain chems via leaf and/or via roots, etc..

4. Does substrate mulm, organic waste content and other de-oxigenating effects play any role at molecular levels for differing fert uptakes in presence of Spezial N like combinations, but arent seen in "other" type of brews?

5. etc etc etc...

.. Apologies for my loud musings, perhaps sounding like a wanna-be geeky.

Hi Tobi, very interesting post and I would definately like to try out your recipe. You state 1ml for 50l. How often do you dose this? Daily?

hi hoggie thanks for your reply.

Luckily I can read German and indeed, for high light setups it is daily whilst for low light setups it is 2 - 3 times a week.
Hi Toby, I have been looking at some of the links you have posted and it seems that most of the users posting their ferts regime do not only stick to the Spezial N - Nitrogen Fertiliser on it own. Besides the Spezial N they add ferts such as ?AquaRebell Mikro Sepzial "Hybrid", ?Kaliumphosphat, ?Kaliumcarbonat, ?Seachem Equilibrium and others.

My question therefore would be, can you sustain a nice lush healthy tank like the ones in your links by only using the Spezail N - Nitrogen Fertiliser and a good iron mix, or does one also have to use this in conjunction with other ferts?

Hi Michael,

those other ferts you have mentioned are no nitrogen fertilizers.
Of course people are adding the other essential nutrients too: They add a trace element mix like the Mikro Spezial Hybrid (but that one is not common... have never started to sell that fert). Most use the Spezial Flowgrow as a trace element mix. and Kaliumphosphat is monopotassiumphosphate... just the German spelling 😀. kaliumcarbonat = potassiumcarbonate etc.

Please remember. The Makro Spezial N is ONLY a nitrogen fertilizer. It's no "all in one fertilizer"

Best regards

I was re reading the thread.
The idea of a + charge on the N source and K+ which has a + charge as well may be why some folks have better growth.

NO3 is a negative charge.

The idea is that a mix of both NH4 and NO3 is BEST much like having a sediment type of source of Ferts (sediment does make a good long term source) and...a water column source.

Most every plant I know grows optimally with a ratio of NH4 to NO3.
This is research based and can be found in Plant Physiology textbooks.

What varies for many hobbyists are the fish loads, feeding, sediment types and age.These are all sources for NH4 but offer virtually no K+. The plant cell's vacuole has mostly NO3 and K+. These are concentrations are governed by enzymes which adapt to different ppm's in the environment. If K+ was stabilized in these aquariums, this should be an issue. Likewise, if the NH4 was stabilized, this also would not be an issue.

If the aquarium lacks a good well feed fish load, then adding NH4 will most certainly be a positive benefit. Many top scapes lack significant fish loads as well have seen. But the NH4 to NO3 ratio is good regardless. And adding small amounts of NH4 will have no negative impact, and if anything, enhance the + ion uptake if at smaller ranges. ADA AS initially is quite rich in NH4, and then declines with a log curve over several months/1-2 years.

There is support for this in research.

But I still think there is something wrong with the methods, adding more K+ should not hinder any growth, there is not support for that. Balancing K+ and NH4+ cations relative to the negative anion ion needs for some hobbyists, might be the issue. Also, I'm not sure how low PO4 is in these systems, this might be a large factor.

If it is higher than 1ppm most of the time.........then it will be hard to say, if lower....then under stress/limiting PO4, adding NH4 will be helpful, actually, in most cases, eg non CO2 or limiting conditions..........NH4 will be preferred in higher amounts vs NO3.

But under non limiting conditions, the effect will not be as great.

Hope this helps.
Any idea if using a combination of Mikro Spezial FlowGrow + Makro Spezial N would cause any clouding or water getting a bit hazy/milkly? Should the macro and micro be used with time in-between dosing them?
Hi Tobi.

Thank you for sharing your tests.
Can you please tell us if anyone have tested the changes of General Hardness GH after using this fertilizer? I would expect that the GH will build up after some time if Ca++ and Mg++ are added every day even in small amounts.

In any case the recipe does make a lot of sense to me, because Mg++ and Ca++ are more accessible for the plants from these salts than from most other salts.

Another question that I have is what would be the counter part fertilizer for PO4? Similar mix of K+, Mg++ and Ca++ PO4 salts or what comes in handy?

Flowgrow is a Ferrousgluconate based fertilizer and can lead to some unproblematic clouding under very few conditions. If you have hard water and add alot PO4 simultanously it could lead to a bit hazy water. We recommend the Flowgrow mainly for soft tap water. Our Eisenvolldünger is made for hard tap water.
The Spezial N is not reacting with the Flowgrow when you dose them after each other to your tank. But you should not mix them in one bottle.

If the clouding appears it should disappear in a short time and has no negative effects.

The GH isn't increasing significantly over time, if you do your regular water changes. Ca and Mg are added only in very small quantities.
I think a mix of PO4 with Mg and Ca isn't needed like the Spezial N. Spezial N is a potassium reduced nitrogen fertilizer to maintain a good potassium:nitrate ratio. The little amount of urea helps some plants maybe too but the big advantage with this fertilizer is that you can easily achieve a higher nitrate level than your potassium level.
In some sitautions a nitrate favoured ratio helps the plants to flourish. But as Tom pointed out... some tanks have absolutely no problem with higher potassium levels.
In my tanks a lower potassium level really helps the plants.

Best regards
I am picking up the Ca++ and Mg++ nitrates next week. I already have KNO3. As soon as I see any results in my tanks I will report them here with pictures and measurements.
Hi Tobi.

I would like to report that this Nitrogen fertilizer does work. I am using it for about two weeks by now and the differences are definite. All plants grow bigger and look better. Especially HC and Staurogyne.
Unfortunately I do not have pictures from two weeks back, so I can not show the difference.
I am using currently ADA fert line and I find the addition of this Nitrogen fertilizer just great.