[APD] RE: DOC

["Thomas Barr" <tcbiii at earthlink_net>]

 >Can we categorize dissolved organic carbon?
 >Is dissolved organic carbon from peat different from dissolved organic
>carbon from rotting food? Is it more or less toxic?
 >Sometimes its hard to be congruent. (ref Gerald M Weinberg)
 
>Steve P
 >P.S. This thread is not about BGA or water changes anymore.
 >P.P.S. My goal is to ask questions that elicit interesting & useful
>information. I have more but they wait.

You have focused the question. This I can talk about.

The humic/fluvicm acids diffused from the peat is QUITE DIFFERENT from the
the much more liabile/more readily avavilable plant detritus or rotting
food.
About an order of magnitude higher.

So these will nutrients will cycle much _faster_ than peat will will.
This is fine if your plants are growing fast. They can handle larger
amounts of waste in these forms.

If your plants are growing slow, then the majority of DOC coming from peat
if fine since it's slowly released.
So if you compare a non CO2 enriched plant tank vs a CO2 enriched plant
tank, then you can see why these two method differ and STILL work well.

The issue of toxicity: well it depends on accreation. A little bit of each
is not a problem in either type of plant tank(Non CO2 or CO2).
But you can push either to it's limits.

If you add more rotting food=> exceeds bacterial/plant/fungal capacity to
assimilate or convert NH4, the carbon is a not large player except as an
electron donor which will cause Redox declines.

The more organic matter you add, whether be from dead fish, food, plant
detritus etc, is not that big of an issue, but in each case it will lower
Redox if you add it to the gravel.

Generally, in moderation, this works fine. But you can see that if you keep
adding this carbon, things will go sour(algae, depeleted O2 levels, H2S in
the substrate).

The bacteria/fungi that will breakdown this matter go to town and use up
O2. 
This will lower O2 and if enough OM is present, will lower the Redox. 

Using peat, due to it's slower breakdown is good in small amounts and
perhaps useful in larger amounts in a non CO2 tank as a source of
nutrients. 
The Lion's share of the nutrients will ideally come from the water column
in the CO2 enriched plant tank.

But DOC I generally think of as something to remove. What's not removed by
bacteria is going to stick around, perhaps interact, perhaps not.
I do not see a use for it, it may hinder/help some species, but these are
substle and something you'd need to watch in a non CO2 plant tank over a
long time peroid.

Non CO2 tanks are just too slow to make some determinations but they are
good for looking into higher DOC levels as it relates to plants.

So the basic take home message:
Food/dead plant leaves-plant detritus-even non or 1/2 growing plants
provide much more biolavailable nutrient sources than peat over time and
the DOC cycles much faster and is easier to break down vs peat. This may or
may not be a good thing depending on your routines/set up etc.

There are about 5-6 main groups of DOC chemical sources. 

I'll eventually write something up in a fiormal book about all this but not
for awhile. 

Regards, 
Tom Barr 

 





  
   

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