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Re: Re: Re: NO3/NH4/PO4 .. plus CO2

At 21.48 09/12/2001, you wrote:
> >Add both. Tweak this later though. For now add more iron(2x a week). Don't
> >worry that it will go to 0.00ppm for a few days(2 or so).
>uhm ... ok! So I'll add iron twice a week and until I read 0.00ppm for 2
>days I dont add anymore.
> >Well the substrate get saturated at some point if you have iron in there.
>i'll measure CO2 directly, not deriving from KH/pH relation.

I didn't disappear .. I was just very busy with work but I want to continue 
this thread.

First of all I must admit that I make a very _BIG_ mistake: the CO2 level 
was completely wrong due to a very old pH probe! :-(
So I had in the tank CO2 around 50/60 ppm with a pH very close to 6.

I had to re-adjust the CO2 valve properly, and it was not simple at all 
since the tank is very tiny, only 20L (around 4 US gallons). It took to me 
some days to inject the proper amount of CO2.
Now I had (with new pH probe!):
pH = 6.7 when lights go out
KH = 2.2/2.5 degrees
CO2 should be between 15ppm and 20ppm, which should be fine.

Then I guess I made another mistake on the filter: I saw the formation of a 
bio-film on the surface of the tank but I didn't understand why ... then 
after some weeks I understood finally and I removed the big amount of 
active carbon that i put in the canister, which was probably clogged and I 
put 1:1 ratio of EHEIM EfixCarbon (which is bigger in pieces, so it 
shouldn't clog as fast as the previous one) and Siporax. I put Siporax cuz 
I haven't add any biological media yet. This was because I hoped (but I was 
wrong) that activated carbon after loosing its adsorbion power, could be a 
good media for bacteria colonisation. But it clogged before :-(

After the CO2 cut, plants indeed have grown slower, and so have done algae.
Eventually they are still there:

As you can see stones are almost cleaned from green algae, but BBA made its 
first appearance in the tank, very sparingly... I don't know if its 
presence is related to the lower level of CO2, the higher levels of traces 
(inducted from the lower level of CO2 => less growth); or maybe it came 
with new herbivore fishes, or maybe it's related to some other factor I'm 
not considering.

>I assume there is no iron in the substrate for what I know. So I don't know
>where PO4 goes when it precipitates.
> >Filter usage, fish uptake etc can be assumed to be negligible. So all your
> >left with is plant and algae uptake. No algae then-> all plant uptake.

Nutrients: I kept them all in the range... NO3 between 3-5 ppm, K is 25ppm, 
Fe is undetectable (but still present), GH=2, Kh=2 ....uhmm PO4....
PO4? well...

NO3 drop per day was around 1.2ppm/1.3ppm so when lights go out, I found on 
the average 2/3ppm readings.
With these values of nitrates, PO4 was always undetectable even with some 
push (up to 0.3/0.4ppm). So I gave a huge drop!
The day before yesterday I raised it up to 1.5ppm, and when lights went out 
it was 0.4ppm. Yesterday after water change I gave other 0.5ppm, and at 
light's out it was <0.04ppm.
I'm thinking of taking it costantly at 0.4ppm or so ... uhm... which is 
_very_ different to give a 0.4ppm push!

What was strange is that at least green algaes, both the thread one and the 
spot one (on the glass) were reducing its presence, especially the spotted 
one on the glass, that was clearly visible!
BBA didn't change a bit! :-(
Plant's foliage is more "polished", kinda more bright! But not all the 
leaves, much more the new ones. Leaves are also greener, so it was kinda of 
phosphorus deficiency, but they are not the normal green yet, and also it's 
not the normal growth yet, it's still too slow.
I also expected more N uptake along with the P's big drop, but the 
assumption of N was constant.
But I had fear to add iron, cuz there are still too much algae in there, of 
every kind!

Today I added a push of trace elements (without iron), and I noticed a 
little more O2 bubbling when light's out.
I think I'll give the P trend another day or two... then I'll make a stop, 
water change and then add iron.
what do you suggest?:-)