Re: [APD] RE: Ca++/K+ in hard water... and K buildup

["Philippe Lemaire" <ph_lemaire at CompaqNet.be>]

Suppose you made water changes with water without K+
Suppose that you change 1/N of the tank water
Suppose that you add X ppm of K+ between changes
Suppose that NO K+ is consumed between changes

The MAXIMUM of K+ you can have is N TIMES X

Philippe


----- Original Message ----- 
From: "Neil Frank" <aquarian_subjects at mindspring.com>
To: <aquatic-plants at actwin_com>
Sent: Saturday, January 10, 2004 12:37 PM
Subject: [APD] RE: Ca++/K+ in hard water... and K buildup


> 
> >> I have been following the threat about high K+ concentrations and Ca
> >uptake and I wanted to add my story to the group.
> >> Some time ago I stopped using RO water to reduce the hardness off my
> >tapwater.  Currently I am using pure tapwater in my tank with a Gh +-20 
> >and Kh +-15. 
> >> I am also seeing distorted growth (which looks like a calcium deficiency)
> >of some plants (echinodorus, ammania, hemianthus, ).  I assume it can't be
> >a Ca deficiency because of the hardness of my tapwater.  I did dose a lot
> >of potassium untill recently.  I followed the method advised by Tom Barr. 
> >Last week I stopped adding the extra amount of K2SO4 after every water
> >change on his advice on this list.  I have more than enough K because my
> >KNO3 dosing is really high (almost no fish in the tank).
> 
> The only thing i can think of adding to Tom's great comments is to ask
> about Pieter's KNO3 dosing and water change regime. K can build up in a
> tank  under certain conditions. Otherwise folks wouldnt be telling us about
> 60-90ppm of K. Most people dont test for K, so it may not even be known. I
> didnt know myself that I had 50ppm in one tank until I tested.
> 
> Build up WILL occur if you are adding more between water changes than your
> plants consumed or that you take away (by dilution) from the water change.
> Thats how it happens.  For example (extreme), if you are adding a tsp of
> KNO3 daily and only changing 20% of the water monthly then the K can easily
> increase. There are examples which are less extreme.  I can produce graphs
> to demonstrate this.
> 
> Because KNO3 provides more potassium relative to its nitrogen than plants
> need, this buildup is more likely to happen if you have few fish (ie.
> little fish food to provide N). This is why I now use KNO3 in combination
> with Ca2NO3. (Both infrequently in small amounts). But I have soft water,
> so the Ca is an extra bonus.
>  
> Neil Frank
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> 
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