Does a calcium reactor also double as a denitrator?

[Gem Tang Rider]

Probably discussed before, but had this thought today.
Considering the slow flow thru a calcium reactor, & the addition of CO2, seems like a calcium reactor may have a denitrating effect.

Whats your thoughts?

[bertoni]

I don't know what bacteria would survive inside the reactors, but it might be possible.

[Randy Holmes-Farley]

Unless you dose organic carbon into it, it may not become low in oxygen or act as a denitrator.

[johns]

Wouldn't the normal left over nutrients in your system water flowing through the reactor be enough organic carbon? You need to dose more or something special/different?

[Randy Holmes-Farley]

If it were enough, then folks with carbon denitrators wouldn't need to add anything. In fact they do need to add carbon to get much drop in nitrate.

[johns]

Randy-

Thanks. I'm not too familiar with carbon denitrators. I was thinking more about conditions necessary to get bacterial growth/colinization. Low flow and normal saltwater with some nutrients seems fine to at least get thinsg started. But I think I understand what you are saying now.

[Randy Holmes-Farley]

Nitrate is used as a source of oxygen to digest organics in low O2 environments, leading to denitrification.

In order to denitrate effectively, one has to first use up the oxygen present. Otherwise, most bacteria will simply chew on the organics using oxygen instead of nitrate. I suspect that simple low flow reactors (like a CaCO3/CO2 reactor) in most tanks won't become adequately low in O2 with enough easily consumed organics left for denitrification to take place.

[johns]

Randy-

Interesting. How is O2 depletion typically happening when vodka and/or sugar dosing then?

What I have read suggested that the increased bacterial growth cause by dosing the extra nutrients was using up the O2 (possibly through denitrification again??) Maybe it's because in vodka/sugar dosing you're basically allowing your whole tank's area for supporting bacterial growth as opposed to a small chamber in a reactor?

[Randy Holmes-Farley]

Two things (at least) can happen with dosing a carbon source directly to the tank.

1. Either bacteria eat it and simply grow in numbers, using up nutrients (not called denitrification, more like what macroalgae does when it grows),

or

2. some of the organic molecules make it into low O2 regions in sand or rock and cause true denitrification. I believe that the former process predominates in most tanks dosing such things, but I've not seen proof of it.

I discuss such processes here:

Nitrate in the Reef Aquarium
http://www.advancedaquarist.com/issu...t2003/chem.htm