Downside of using carbon?

[Lemeshianos]

What is the downside of using carbon?
I've seen people recommend for and against it. I know the positives of using carbon but I can't think of a downside other than that its in the sock and could collect debrites.

 

[Randy Holmes-Farley]

Some folks are concerned about export of trace elements (metals) that are bound to the organics that bind to the carbon. In general, that does not concern me, and I'd typically consider it a benefit, although with a lot of macroalgae, you may want to dose iron.

 

[Lemeshianos]

so carbon not only absorvs the "bad" stuff but can also absorb some of the chemicals you want in the water for the growth of macroalgea or something?

 

[Randy Holmes-Farley]

That is what some people give as a negative, yes. I generally consider that a positive since many of these metals are present in excess.

These have more:

Reef Aquaria with Low Soluble Metals
http://www.reefkeeping.com/issues/2003-04/rhf/feature/index.php

Organic Compounds in the Reef Aquarium
http://reefkeeping.com/issues/2004-10/rhf/index.htm

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 1: The Salt Water Itself
http://reefkeeping.com/issues/2007-03/rhf/index.php

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 2: What Chemicals Must be Supplemented
http://reefkeeping.com/issues/2007-04/rhf/index.php

The "How To" Guide to Reef Aquarium Chemistry for Beginners, Part 3: pH
http://reefkeeping.com/issues/2007-05/rhf/index.php

The “How To” Guide to Reef Aquarium Chemistry for Beginners,
Part 4: What Chemicals May Detrimentally Accumulate
http://reefkeeping.com/issues/2007-09/rhf/index.php

 

[BigJay]

Some people say that carbon can leach phosphates into the water. Using a quality carbon, this hasn't ever been my experience. Randy, that should only happen if the carbon is washed with phosphoric acid right?

The only issue I see to carbon use is cost, since replacing it frequently gives the best result IME. Using it for long periods of time (over a month) may allow detritus to build up in the reactor that will break down into nitrates.

 

[Randy Holmes-Farley]

I think the concerns about phosphate on carbon are mostly due to inaccurate extrapolation from a test in a cup to a real tank. I discuss it here:


http://www.reefcentral.com/forums/showthread.php?s=&postid=12753198#post12753198