Activated Carbon Granules question

[Enthrol]

As a new hobbyist I'm trying to learn what the different tools we have available to us do.

 

I'm running into a problem finding out what Activated Carbon actually removes. For instance, GFO removes phosphate. For Carbon though the best I have been able to find is it binds organics, toxins, odor, and yellow pigmentation. 
 

What should I expect from Carbon when it says organics? Lower nitrate? 
 

Just want to know what I can use it for other than toxins, odor, and discoloration so I'm using the tool correctly.

[Clown79]

It doesn't have a huge impact on nutrients.

 

Most ppl use it to help reduce toxins from corals, preventing chemical warfare.

 

I like to use a small amount in a media bag which I change every 3 weeks 

[MrP]

Organics are introduced mainly through fish waste and are the primary cause of yellow tint in water. Organics play an important role in the ecosystem. In most cases, a skimmer is all you need to remove excess organics. You don't want to completely strip your water of organics. 

[Enthrol]

12 hours ago, MrP said:

Organics are introduced mainly through fish waste and are the primary cause of yellow tint in water. Organics play an important role in the ecosystem. In most cases, a skimmer is all you need to remove excess organics. You don't want to completely strip your water of organics. 

What if I'm not running a skimmer?
 

I'm not looking to add carbon right now, but based on Clown's response about toxins I might when I have a healthy stock of corals. My tank was set up relatively recently so I dont have much in the way of livestock yet, just looking to better understand.

[DreC80]

Depends on what type of corals you plan on keeping.  Are you going for a lot of leather corals?  If so, probably not a bad idea to run some carbon...especially in a smaller tank.  Some folks run it for a few weeks then take it off for a few weeks.  Some alternate carbon and gfo.  Some don't run any.  Some probably run it all the time.  I'm not a fan of putting things in my tank just because it's available.  I try to be intentional about it to help solve a specific problem.  Carbon does help clear up the water, which allows more light to get to your corals.  Just something to keep in mind so you don't light shock them.

[mcarroll]

Activated carbon removes a wide variety of dissolved material from the water.  Organic material is relatively large and irregular, so it's very good at removing them, but it's not limited to just that.  Use as-needed and with moderation.   I've gone 10+ years and used barely a liter of activated carbon in all that time.

 

Activated carbon's use should not be necessary every day in most tanks, and in fact it's know to cause problems with some livestock when used all the time.  Tangs most famously.

 

Carbon's "activated" state is most-active when it's first placed in the water, and it's effect gets progressively weaker at an exponential rate after that.  

 

Here's a graphic that does a decent job illustrating how activated carbon works:

 

This also makes it clear why activated carbon gets less active so quickly.  

 

Not only do the "activated" pores literally fill up with the material the carbon is filtering from the water, but once bacteria overgrows the carbon surface (guaranteed to happen in a month or less), nothing significant is getting in or out since the pores are blocked.

 

This is fine (and desirable) when you're creating a habitat, such as we do with live rock or the various ceramic alternative medias.  Not fine when you're using it expressly for filtration.  Bacteria will eventually reduce activated carbon to bio-media status.  

 

(Could be why it seems beneficial to run all the time in some tanks...it's not really being activated carbon after a while, it's just being a little more bio-media.  Carbon is useful in that state in a garden as bio-media...in fact kinda unique if you look at activated carbon in its "terra preta" form.  Again, just not useful for filtration in this state.)