[kekon]

The title should really sound like a question as i'd like to ask you about your personal opinions about this chemical element.
The main thing i'm quite sure of is that adding more K help plants to be more resistant to higher NO3 levels which in my opinion is the main culprit of deformations and stunting in new plants leaves. High K levels (30..50 ppm in the water column) can work very well but it comes at price. When there is not enough boron the growing tips may be malformed and dwarfed. I noticed that more boron must be added when K is higher. This is not a problem when tap water is used in a tank but it can occur in tanks where RO is used only.
This is why some people have terrible experiences after adding more K. To make things worse too much K can block manganese uptake (but this is eliminated just by adding more micro fert)
But now new probblem occured in my tank. Anytime there is more than 10 ppm K almost all plants became light-yellow on youngest leaves. I haven't solved the problem for nearly a year.
This suggests that someting is blocked especially non mobile nutrient which i can't find. When K is decreased back to 10 ppm all the plants regain their rich collors. This happens when K2SO4 or KHCO3 is used as a source of K. Adding Fe doesn't help at all; dding more Mg doesn't work either.
I talk to some people who add much K but they don't have such issues. Two days ago i added more NO3 (to at least 10 ppm) but i haven't seen much improvement so far.
Do you have any experience on the subject ?

 

[Round Head]

Yes, I have the same experience.
I have very high lighting, use RO/DI water, and ADA aquasoil.
I read a thread once on high dosage of K for this type of system.
My plants got stunt real bad. So I went back to high N and low K and they seem to be getting back into shape. Sorry, I don't have any numbers. I just have an 80gal so I dose 40ml N, 20ml K, and 20ml Phos and alternate with 40ml CSMB, 20ml Fe, and 40ml N.

 

[kekon]

I see little improvement after dosing more NO3; leaves have changed their colors from light-yellow to more greener color but it's not perfect yet. I wonder hot it works with Seachem Equilibrium which has hight potassium content (50 ppm K when recommended dose is used). People who use it usually don't have any issues with plants coloration.

 

[Leonard]

When I dose more KH2PO4 or K2SO4 algeas thrives better, I use to keep K and PO4 as low as possible to get away from algeas.

 

[kekon]

I've never had any issues with algae at high PO4. I kept 1 ppm PO4 for over a year and no algae appeared. But this must be kept together with higher NO3 (10 ppm for example). Otherwise algae will thrive. The worst situation takes place when there is more P than N. This really can trigger massive algae bloom.

 

[Champagnero]

Hi Kekon,

I've made similar observations. If I up my potassium dosage my plants grow kind of whitish. The older leaves look normal but the shoots have severe chlorosis. Mg, Ca, Fe, Mn, Zn, Cu, Bo do not help. I tried nearly all miconutrients separately without success.

If I decrease the potassium concentration everything greens up a bit. But still testing on this.

At all I have no clue why this problem occurs. But for now I'll reduce my K dosage a lot .

Best Regards
Tobi

 

[kekon]

A person i know adds lots of K after each water change - 50 ppm. He doesn't notice any chlorosis but he adds extremely high micro doses; about 10x more than recommended TMG dose. I tried to add such huge micro doses but it ended up with toxicity symptoms (stunted growth, deformed growing tips and lots of thread algae). He uses very soft water GH = 3.

 

[kekon]

Well, the situation has improved. I added more NO3 to reach 10 ppm. Plants got richer colors but they're not so intense as they should. The next step will be setting "recommended" 20 ppm of K.