Re: DOC`s
Well if they are oxidized eventually, they can add a little, and I mean very little CO2 source for plants.
A little more current and turnover etc would do a lot more to add DIC.
In non CO2 systems, I think they play a minmal role as far as the plants are concerned.
As far as the bacteria are concerned, carbon is everything.
Like us eating bread, pasta etc, our carbs...........
Bacteria can become carbon limited and since non CO2 tanks mainly are a balanced system, the bacteria can use more DOC to help reminerlaize the other nutrients from fish waste.
In CO2 enriched systems, we cannot wait for this waste to be brokened down since growth is amplified.
So we add inorganic CO2 and inorganic nutrients.
Non CO2 can work without any inorganic ferts, but many nobn CO2 tanks cannot grow nearly as many species due to this issue.
If you add just a little inorganic ferts once a week, then you can grow more species and the plants look better in a non CO2 tank.
Regards,
Tom Barr