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Re: Aquatic Plants Digest V2 #1086

Guillermo Vega-Toro wrote:

>Can anyone recommend a good commercial fertilizer with Potassium? I
>think that some of my plants are showing K deficiency now that I am
>adding CO2 and increased lighting (220W on a 60-gal tank, used to have
>only 80W). The new leaves of two Amazon Swords are getting translucent
>and whitish in color. Before CO2 and increased light, these Amazons were
>not growing much, but were a lot greener. Soon after CO2 and increased
>lighting, the plants exibited a tremendous growth spurt and lots of
>oxygen bubbles. Last weekend, for the first time, Nitrates measured 0
>(used to always measure between 10 and 20 ppm). 

First off since the plants have reduced the nitrate to 0 I would say they
_Had_ all they needed.  Now they are nitro limited, so do forget that.  The
increase in both light and CO2 levels will eventually make the plants
consume a lot more nutrients then they did in the past so all your dosing
will increase.  Just do not concentrate on one element of a fertilizer when
you will need nitro according to your readings also and if it is not
provided you amy end up with a PO4 excess and thus an algae bloom.  As far
as the white sword leaves and other changes you will see in the plants,
remember you just drastically changed the environment.  Some plants have
adapted to the old conditions and their leaves may not be ready for the
change, but the new ones will.  

>I currently fertilize with Kent's Freshwater Plant supplement (2 or 3
>capfuls on each weekly 15 gal water change), and push Flourish Tabs and
>laterite balls on the base of the plants. I also just started adding 4
>drops of Dupla Plant 24 every day. 

OOoooooooo  you are mixing approaches:)  Consider yourself slapped with a
wet ell.
   That said, lets see here.  #1) Kent's product does have K in it although
I do not think it is enough.  Flourish also has it, again though I am not
sure if it is enough.  Again the Dupla drops have it, but Duple does not
plan on supplying all of it in the daily drops.  Dupla has a tablet that you
add during water changes, if I remember correctly that has most of the
potassium needed in the Dupla Method.  So you could pick up that.  Outside
of the Flourish tabs you are almost full Dupla, why don't you just go full
Dupla and be done:)  From what I have seen, most of the commercial
fertilizers, aquaria or terrestrial, do not have enough Potassium.  I went
with K2SO4 from Homegrown Hydroponics and am happy with the results.  I
would suggest you keep your eyes open, I do not think K is your only
deficiency, Nitro is another one.  I would suggest that you pick an
approach, Dupla since you are all but there, and go with that.  Once you
tank has stabilized in it's new conditions you can start looking for
problems again.  

>I assume that the deficiency is not Fe because the leaves are not
>yellow. Is that a correct assumption? 

This assumption means that there is some Fe in the water.  I like to look at
red plants.  Is the red a dark red or is the Pink in H. poly "sunset" a nice
pink.  I assume that by the time you have an iron deficiency show up as a
sever chlorosis you have waited to long:)  

Good luck,