Carbon dosing- why some systems react differently?

[Reefahholic]

I’ve noticed some systems are fairly quick to start dropping NO3 or PO4, but in others I’ve seen NO3 or PO4 start to climb. I have my own opinions why is might happen, but I’d love to hear what others have to say. Especially those who have carbon dosed for years or somebody like @Randy Holmes-Farley or @Hans-Werner who may have a good understanding as to why this is may happen in some tanks and not in others. Or just in general why this may happen in any tank. Is this a temporary thing? I’ve seen a few where it seems to climb for a while. Let me know your thoughts.

 

[naterealbig]

Have you checked here?

https://www.reef2reef.com/threads/looking-for-thoughts-on-organic-carbon-dosing-and-nitrate.971856/

 

[MBruun]

I'm no expert or scientist, but I think the different pattern in reactions in different aquariums are caused by the dosed carbon source vs the type and amount of "free" carbon in the aquarium, and the bacteria present in the aquarium.
Meaning one system will react different on different types of carbon

 

[Randy Holmes-Farley Verified Community Expert]

I’m not sure what the issue is exactly.

In my tank, I tried a very wide range of doses, and even at very high doses of vinegar (410 mL per day in a 120 display with about 300 gallons total) the effects never seemed to relate to low nutrients.

We haven’t really discussed the export part of the equation much, but if the added bacteria and other organism tissues are mostly recycled in the tank system, rather than exported, the effect on nutrients may be less. Also, if there is little denitrification taking place for whatever reason, nitrate reduction will be less.