kekon

I've just come to some conlucions recently but i'm not quite sure... In the past when i set up my first planted tank i used NPK fertilizer where the nitrogen was in urea form or most probably - guanidine carbonate form (CH5N3)2.H2CO3. Also, i used only pure RO water reconstituted so that the water in my tank had only 13 ppm Ca and 4 ppm Mg (Ca was from CaCO3 only). Despite low Ca, Mg and almost not-detectable PO4 levels my plants grew like crazy. NO3 was also quite low, it never exceeded 10 ppm. CO2 was max. 15 ppm.
I never had deformed young leaves, burned tips or stunted tips etc. I estimated i had about 10..15 ppm K as well. When i switched to use KNO3 instead of that NPK fert things went very bad. All my alternatera and rotalas and also umbrosum looked like burned (severly deformed new leaves). Additionally, the total growth was stunted. The first thing i suspected to be wrong was low Ca so i increased it up to 40 ppm but it didn't help much. I tried everything: changing Ca/Mg ratios, used other salts to reconstitute RO, changed micros levels and ratios, high NO3 and PO4, low NO3 and PO4 - it all failed ! Only when K was close to zero ppm plants started to grow better but K deficiency showed up on other plants. A friend of mine is experiencing very similar problems. So, i stick to the opinion that the culprit may be nitrogen form because when i used it (guanidine carbonate and probably NH4HCO3) i had no issues.

Edouard

Hi Kekon,

I am facing similar problems (see my thread: http://www.aquaticplantcentral.com/f...-included.html) and I have read your posts thoroughly.

Don't you think the macros could have been the limiting growth factor (levels of PO4 close to 0 you said) before?
By adding nitrogen, phophorus and potassium the plants now grow more and the limiting factor has changed. It could be one trace element?

I would be surprised if your problem comes from the use of NPK as many people are very successful with them.

Good luck.

kekon

But which one ? I haven't been able to find it for 10 months...

Salt

NH2 is part of the amine group which is used to make plant proteins. Nitrate (NO3) isn't. Because of that plants are able to utilize NH2 very easily. Plants must convert NO3 to a usuable form first.

Guanidine is an excellent nitrogen source for plants. The three NH2's are bound to a carbon atom that makes it harder for algae to use it.



Seachem uses it in their Flourish Nitrogen product.

kekon

I've just ordered some guanidine carbonate - (CH5N3)2 * H2CO3. I could also buy CH5N3 * HCl but i rejected the idea because it would also add chloride. It's not possible to get pure guanidine (i didn't find it anywhere). The guanidine carbonate solution (5%) has high ph = 11. I suppose that the salt is used in the NPK fert i used because it also has high pH (above 10). I have one concern about guanidine carbonate: is there any additional enzyme needed for it to successfully utilize by plants ? (for pure urea for example - uraese is needed. The uraese contains nickel ions)

hoppycalif

Kekon, please keep us informed of your results with guanidine carbonate. This is very interesting!!

kekon

I will However, i've just begun to dose NH4 (from NH4NO3 salt) but only 0,15 ppm NH4 a day. I know some folks will "bite" me for doing that...
The guanidine carbonate will be available next week. A friend if mine began to dose guanidine a few days ago but we have to wait some time to see the effects.

Salt

Guanidine nitrate would probably be a better nitrogen source.

czado

Here is the lowest price for Guanidine Nitrate on Froogle. Also 98%.

What is the formula for calculating how much of CH5N3.HNO3 becomes N from Guanidine and how much becomes Ntrate? Just curious. (I understand one could calculate total N using molecular weights.)

Thank you.

kekon

To calculate it you just need to calculate atomic mass for CH5N3 * HNO3 taking each element from the periodic table:

C: 12
H5: 1 * 5 = 5
N3: 14 * 3 = 42
H: 1
N: 14
O3: 16 * 3 = 48

Total mass: 122:
NO3 mass: 14 + 48 = 62

NO3 / 122 = 0.508 -> 50.8%

the rest of ntrogen: N3: 42
N3 / 122 = 0.344 -> 34.4%

So, guanidine nitrate contains 34.4% of NO3.