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Unread 01/04/2018, 08:42 PM   #48
Dan_P
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Join Date: Aug 2014
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Quote:
Originally Posted by bertoni View Post
I agree that creating more net biomass is likely to consume nitrogen and phosphorus at a higher rate than other consumption patterns. That said, a lower consumption rate might be fine. Whether a tank takes an hour to consume a daily dose of vinegar or 12 hours, either way, nitrogen and phosphorus seem to be converted to a skimmable form in some tanks, from what we can see. The biomass must stop increasing at some point, or the tank would be filled (literally) with bacteria, but that does not imply that export stops, or won't be effective. For all we know, dying bacteria or their remains might be highly skimmable.
Isn’t the notion of carbon dosing essentially growing bacteria? And if so, the rate of increase of a bacterial population depends on conditions, in this case, increasing carbon increases bacterial biomass (I wonder if one gram of carbon results in some tenths of a gram of bacteria. Sounds like too much, there is predation and export as you point out.). And you are right, we typically don’t fill our aquarium with bacteria, though that would be an interesting calculation. 40 gallons of bacteria equals how much vodka. However, when the nitrogen or phosphorous is used up, I am pretty sure the larger bacterial population has few choices if any but to die or form spores. I think to move forwards at this point we need to answer the question how many bacteria are generated from a mg of NH3. I don’t know off hand what a typical bacterial stoichiometric ratio of elements is but assume 5% by weight is nitrogen. That gives 20 milligrams dry weight of bacteria. Spread throughout the aquarium that amount would be invisible, yes? And if skimmable, I would guess removed or diminished in number quite easily. There must be a portion lost through predation too.


Quote:
"Harvesting" is a bit ambiguous here.
I have macro algae on the brain


Quote:
I agree that a visible slime is one possibility. I'm not so sure that bacterial crashes are going to be a significant danger. Bacterial populations can increase quite rapidly, generally, so I'd expect that a crash would be undetectable with hobbyist equipment. Stopping feeding seldom seems to cause issues, for example, and it's actually a step that I often recommend when dealing with various nutrient buildup or tank crash situations.
If one suddenly stops dosing carbon and there is no ammonia spike, you have not killed off or severely impacted the system’s ammonia processing capability, i.e., no crash, right?

So where are we? Carbon dosing could impact autotrophs but we have little or no data to say this is a large downside. In principle, we should remove the extra bacteria we grow with carbon dosing to maximize nutrient export but this might not be totally necessary if that bacterial biomass is assimilated and locked up long term in some other biomass, e.g., the tanks population of protozoa, rotifers, amphipods, etc. Are we done here?


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