[APD] RE: Ca++/K+ in hard water

["Thomas Barr" <tcbiii at earthlink_net>]

> 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).

Well with a GH of 20 degrees, I think it's VERY un likely there's a lack of
Ca++:):):)
The literature certainly states that at high K+ levels, it's effects on
plants are greatly reduce when the Ca++ levels are increased abnd the pH is
stabilized.

> I was thinking that I get the distorted growth because a lack of
micronutrients.  I do add them but the tracemix I use is self prepared.  I
use for example Borax, ZNSO4,..and mix them in the right proportions with
demineralised water.  The Iron I use is chelated (FeEDDHA).  The thing is
that only Iron is added bounded to a chelate and all the other
micronutrients are not.  Furthermore my tapwater is very hard and therefore
it is impossible to lower my pH values below 7.  This means that only the
Iron will remain accessible for uptake by the plants.  Can this be the
reason of the distorted growth and can't it be the solution to the problems
some guys think are Ca deficiencies?  >

No, you need more traces in harder waters generally.
More CO2 perhaps.Good measurements of pH and KH are key at high KH.
Note that a difference between pH 7.4 and 7.6 yields a CO2 difference of
10ppm. 7.2 to 7.4 a difference of 13ppm.
So a little error will throw things way off.
 
> Are commercial trace mixes like TMG also working well with higher ph
values than say 7.5?

Yes.

> What is a normal concentration of K+ in tapwater when it is as hard as
mine?  What is is's contribution to high Kh and or Gh?

Generally pretty low.

> Pieter Cool  From Aaron_Colichia at Dell_com Fri Jan  9 11:32:54 2004

I'd try this having had similar hard water: Add more traces, 3x a week. Up
the CO2 a little. 
Give any change in the trace routine/growth differences at least 3 weeks
with most plants. Don't assume the change in the first day etc is the total
cumulative effect.
Try your best to rule out other poitential issues(CO2 etc)

Regards, 
Tom Barr




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