# Massacred by potassium



## kekon (Aug 1, 2005)

Here I posted some photos taken when K in my tank exceeded 20 ppm and where it was max. 10 ppm. I believe that high K levels may not harm plants but others conditions must be met to allow it. I discovered that higher Ca and Mg levels prevent plants from being "overwhelmed" by K at higher levels.
Things go better when Ca = 30 ppm and Mg = 8 ppm.


----------



## yildirim (Nov 25, 2004)

It looks to me that when you increased K, your other macros bottomed, especialy N.

YILDIRIM


----------



## kekon (Aug 1, 2005)

I keep NO3 at 10 ppn and PO4 at 1 ppm all the time. I don't think there are too low.


----------



## HeyPK (Jan 23, 2004)

30 ppm of calcium is too low for quite a few aquarium plants. It may be that the symptoms you show are strictly due to calcium deficiency, rather than too much potassium


----------



## kekon (Aug 1, 2005)

Some time ago I used commercial salt for reconstituting RO water (called "Hydro Mineral") Recommended dosing gave 13 ppm Ca and 4 ppm Mg. When I started to dose KNO3 and KH2PO4 problems with twisting and deforming began. So I simply doubled recommended dose which led to 26 ppm Ca and 8 ppm Mg. Plants looked much better then. Due to the fact that the exact contens of the Hydro Mineral is unknown I bought CaSO4, CaCl2 and MgSO4 to make my own mixture. However, it is not simple to get 30 ppm Ca from CaSO4 and CaCl2 since it adds to much SO4 and Cl.


----------



## plantbrain (Jan 23, 2004)

One of the biggest issues in dealing with nutrient responses is maintaining good CO2.

Adding a limiting nutrient to a tank will increase CO2 uptake.
It's also not an either, 100% limited or 100% excess, there are gradations of CO2 stress, N stress etc.......

Regards, 
Tom Barr


----------



## Salt (Apr 5, 2005)

I am currently in the processing of testing in my own tank, but I am beginning to give very serious thought to magnesium levels. I believe it may be that magnesium levels above 10 ppm may be the "secret killer" in many aquatic plants.

I think this is very significant information and I think it is being WAY overlooked.

Edward's pic of rotala showing growth stopping with magnesium above 10 ppm and starting again with magnesium below 10 ppm:










So it *may* be "massacred by magnesium."

To test magnesium levels, you subtract calcium hardness readings (as CaCO3) from total (i.e., "general") hardness readings (as CaCO3), then divide by 4.11796 to get magnesium specific levels in ppm.


----------



## Salt (Apr 5, 2005)

HeyPK said:


> 30 ppm of calcium is too low for quite a few aquarium plants. It may be that the symptoms you show are strictly due to calcium deficiency, rather than too much potassium


This is another big problem (as I see it) in talking about levels... not understanding what equivalence the poster is talking about.

If he's talking about *actual calcium* ppm, then that equates to a CaCO3 equivalence of 75 ppm, or 4.2 degrees. Hardly "too low" at all.


----------



## kekon (Aug 1, 2005)

Well, I know that some plants don't like too much magnesium but in my case it turned out that plants grow better when increasing Mg from 4 to 8 ppm. A friend of mine began to use only tap water of GH = 16 (there is probably much Ca and Mg) and his plants grow better. All the problems with "massacre" bagan after stopping to use commercial NPK fertilizer which consists N in urea form, K and P and - according to the producer - biostimulators. Noone knows what chemicals are used as biostimulators in the fertilezer. Anyway, I will observe the results with Ca and Mg and write about them.


----------



## HeyPK (Jan 23, 2004)

> If he's talking about actual calcium ppm, then that equates to a CaCO3 equivalence of 75 ppm, or 4.2 degrees. Hardly "too low" at all.


I was talking about ppm expressed as CaCO3, not simply Ca. I just had an occurrence of calcium levels that low, and it stopped growth of water sprite and caused tiny, distorted leaves in _Hemianthus micranthemoides_


----------



## jude_uc (Feb 7, 2006)

I've found Ca and Mg to my best friends in my tank. My growth always seems to putter out if I neglect them. I don't know exact numbers now, but I'm certain both of those are well above recommended values. If I go below for either of them, several of my plants start showing degeneration (water sprite starts to fragment, valisneria starts to melt, etc). 

-Adam


----------

