# KNO3 - Too much potassium



## kekon (Aug 1, 2005)

Recently, I have observed leaf curling on such plants like Umbrossium and on some leafs of Hydrophila Polyperma. Together with my acquaintance we came to the conclusion that there was too much potassium. So I tested the water from my tank in the laboratory and it showed there is 27,2 ppm K - isn't it too much ? Previously I was dosing KNO3 and KH2PO4 to obtain 10 ppm NO3 and about 1 ppm PO4. Together with NO3 I was dosing K. Now I have got expected levels of NO3 and PO4 (10ppm and 1ppm respectively). NO3 was dosed in 5ppm doses for 4 days in a row (so, according to the fertilator dosing 5 ppm NO3 from KNO3 I added about 12 ppm K. Before KNO3 dosing was started it might have been about 15 ppm K). The problem is how to maintain 10ppm of NO3 without the K excess ? (as far as I know the recommended level of K is 10..20 ppm) Besides, we don't know how fast the postassium is eaten by plants (apart from NO3 and PO4 which can be easily measured my means of test kits). Of course it is possible to test K level in a laboratory more often but it would be too expensive and inconvenient. I thought about using CaNO3 as a source of NO3 (it would probably increase GH but no so much). So now I'm entangled in confusion....


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## hoppycalif (Apr 7, 2005)

I dose KNO3 and KH2PO4 too with no problems that I would consider a K surplus problem. In fact I have read that you can run K pretty high and it does no harm. Some people even dose K2SO4 (I think that is the compound) to increase K even more.


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## plantbrain (Jan 23, 2004)

You can view some past AGA contest winners who had over 100ppm of K+.

The normal recommendations vary but 20-30ppm has been used for about 10 years now in the USA, we have not noted any issues.

routinely I've dosed to 50ppm + without any issues related to any plant species (about 300 aquatic species).

also, you do not need to add K2SO4 if you use KNO3, the plants should always have plenty of K+ if you dose KNO3.

Regards, 
Tom Barr

www.BarrReport.com


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## kekon (Aug 1, 2005)

The more I know the worse is the plant growth... But the problem still remains: what is the cause of leafs curling ? Before I was dosing KNO3 I didn't have problems with Umbrossium and leafs curling. The problem appeared after increasing K dose (nothing else was changed).


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## plantbrain (Jan 23, 2004)

Mg perhaps, what is your GH?
What else do you add?
CO2/NO3/K+ you can rule out.

Adding some Gh boosters, perhaps a mix of CaCl2 and MgSO4 can help.
Water changes bring in sources of GH also.
Adding more traces also can help if the KH increased.

Regards, 
Tom Barr

www.BarrReport.com


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## kekon (Aug 1, 2005)

Well, now I have:

GH = 4
KH = 3
pH = 6.6
PO4 = 0.5..1 ppm (from KH2PO4)
NO3 = 7..10 ppm (from KNO3)
K = 27.2 ppm (tested in laboratory)
T = 24C

The RO water is prepared using commercial mixture (called "Hydro Mineral" and produced in Poland) consisting about 12 ppm Ca, 4 ppm Mg, 2 ppm K (using producer recommended doses). Ca comes from CaCO3, KH from NaHCO3, Mg probably from MgSO4. Some people who had the same problem with K argue they solved the problem after decreasing K level ("curling problems" were on decline) although I don't know what levels of K they had before and after the problem was solved. The only advantage of increasing NO3 and PO4 to 10 and 1 respectively is elimination of thread-like algae and making some plants to grow exactly upwards (for example, Rotalla Rotundifolia was growing sideways before NO3 and PO4 were increased)
Besides, I've got impression the total growth is worse


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## plantbrain (Jan 23, 2004)

Well, then you are left with doing water changes with that mix, are you sure you have the right amounts?

K+ does not do this, it's an indirect effect causing a nutrient deficency.

By increasing K+, you drive a nutrient down.

Look, we have dosed huge amounts of K+, never had any curl issues. I've done this so many times I've lost count over 10 years.

Some folks claimed that it was K+, but when I did it, the same conditions etc, as well as the folks here in our local club, which have nearly 200 members now, no one has observed this. so it was not repeatable based on the condition and notion that excess K+ caused any growth differences at 10 or a 50ppm.

Many of the membership here add K2SO4 on top of the KNO3. 
This is not needed but they do it anyway, it does no harm. I've seen their tanks.

My personal bet is that you have a poor test kit for NO3/PO4 or do not add enough traces with the K+.

That would produce the curling.
Good CO2 will solve most of the algae related issues, from there it's mainly adding enough consistently.

I'd suggest more water changes and dosing, and less reliance on test kits and the readings.

If you increase nutrients, make sure you increase them across the board.
You said you also increased the NO3/PO4 as well.

Regards, 
Tom Barr


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## kekon (Aug 1, 2005)

Thanks for help. The only thing I can do now is decreasing KNO3 doses and keeping NO3 at 5 ppm (the test kit is good, some folks tested NO3 from their tanks in laboratory and using the kit and the results were practically the same). If the experiment fails, I will increase trace doses. I'll write something about the experiment results here.


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## kekon (Aug 1, 2005)

here's a picture of my Ubrossium:
http://fonosun.ita.pwr.wroc.pl:8880/~seku/kekon/DSCN0026.JPG


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## plantbrain (Jan 23, 2004)

M umbrosum tends to do best with higher dosings of KNO3 and good traces(I'd add more of both).
CO2 looks good. You can add a little MgSO4 and more traces.

How big is the tank?

Regards, 
Tom Barr


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## kekon (Aug 1, 2005)

Tank capacity is 200 liters. Lighting is composed of 5 30W fluorescent bulbs:
3 x 4000K (Ra = 90%) 2 x 6000K (Ra = 90%) and 2 x compact bulbs (Philips) 6500K to light tank sides (without the bulbs tank sides were too dark). I thought the bulbs were chosen incorecctly (wrong color temperature) but it turned out many folks had identical ones and everything was OK (the light is a bit too yellowish but I can replace one 4000K bulb with 6500K one).
As far as Mg is concerned, I can increase it (I have some MgSO4). Now, Mg level is about 4 ppm.


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## plantbrain (Jan 23, 2004)

Here: do this routine:

Add weekly:

KNO3 2-3x a week: 1/2 teaspoon
KH2PO4 2-3x a week: 1/8 teaspoon
Traces, Tropica master grow or equilivalent: 10mls: 3x a week
Make sure the Ca is more than 10ppm, the Mg is 4 or higher.

weekly 50% water changes.

That will address any nutrient issues without a test kit.
The rest is simply tweaking CO2 levels.
The above routine has been done by many for over 10 years and is popular for newbies and old time folks alike. 

CO2 is the main issue if you have a problem.


Regards, 
Tom Barr


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