Carbon dosing & iron

[Kairus]

What is iron's role in the growth of the bacteria that uptakes carbon, phosphate, and nitrate? Does this bacteria utilize iron? If so, then a system which does not have many water changes could potentially become iron limited over a long time period?

The extended Redfield ratio is said to be 106 C:16 N:1 P:0.1-0.001 Fe.

I've read Randy's article on iron, and some of his posts and they seem to relate mostly to macroalgae's depletion of iron.

 

[bertoni]

Almost every living organism requires iron to survive, so carbon dosing might cause more iron export. That would depend on exactly what's being exported, and we don't know what that is.

 

[Randy Holmes-Farley]

I think nonphotosynthetic bacteria probably use less iron than photosynthetic organisms in general since iron plays a big role in photosynthesis, but all organisms use it, as Jonathan mentions. The same uptake of iron would be true if fish or corals were using the same nutrients to add tissue mass, so just because bacteria use the nutrients instead of something else does not necessarily imply more iron consumption.

I don't generally think that iron dosing has been shown to be useful just because of organic carbon dosing. But dosing it is also not difficult or expensive. So it is easy to try and see if it has any effects, positive or negative.

 

[Kairus]

I think nonphotosynthetic bacteria probably use less iron than photosynthetic organisms in general since iron plays a big role in photosynthesis, but all organisms use it, as Jonathan mentions. The same uptake of iron would be true if fish or corals were using the same nutrients to add tissue mass, so just because bacteria use the nutrients instead of something else does not necessarily imply more iron consumption.

I don't generally think that iron dosing has been shown to be useful just because of organic carbon dosing. But dosing it is also not difficult or expensive. So it is easy to try and see if it has any effects, positive or negative.

Interesting. I'm considering using Seachem Reef Plus which contains small amounts of iron (0.009 mg per 1g), as well as iodine (0.18 mg per 1g) and a mixture of other trace elements and vitamins and aminos. Not really sure the rest of the stuff is *needed* but I don't expect any harm from putting them into my tank sparingly.

I'm really interesting in how elements like iron are depleted in a reef tank over long periods of time without regular water changes. I only change about 8-12g per month on my 72g.

 

[Randy Holmes-Farley]

FWIW, you'll have a hard time knowing if iron is depleted because it is likely below detectable levels all of the time (at least using any home kit).

I discuss that here:

First Iron Article: Macroalgae and Dosing Recommendations
http://www.advancedaquarist.com/issues/aug2002/chem.htm

Second Iron Article: Iron: A Look at Organisms Other than Macroalgae
http://www.advancedaquarist.com/issues/oct2002/chem.htm