How often should I be changing out carbon?

[Mojado]

I searched this site, but was only able to find posts from 2006 or 2007. And in this hobby, that might as well be back in the dinosaur era.

 

So, how often should I be changing my carbon out?

 

Summary as of 1/30/2014 of posts 2 thru 24:

 

Prior to posting this topic, older posts I had read (from 2006 and 2007) recommended once every 90 days. The posts below, however, recommend changing carbon out from once every two to three weeks, some folks leaving the carbon in for up to a month between changes, though most responses below give no reason for choosing this interval.

 

One guy changed it out *only* after seeing water clarity issues or noticing coral stress due to allelopathy, basically coral is having issues from non-desired plant life in the tank (algae, etc).

 

Another dude below doesn’t run carbon all the time *unless* there are water clarity issues. There was no mention of how often that is, though.

 

Polarcollision found some words on-line that say that carbon does most of its business in the first 2 days, then no longer is as effective . . .it is then useless after 14 days due to bacterial colonization. This sentiment was echoed later, though that person said carbon is useless after 24 hours.

 

The conclusion I can reach from responses below is that anything less than a month is good, though carbon may not be doing anything past 14 days. If carbon is no longer useful after 24 hours, changing it out once a month is the same as running carbon once a day every month. . .assuming leaching back into the water column is minimal (this is a safe assumption). I’ll update this summary if more folks chime in with differing opinions/anecdotes . . .or better yet, data!

[Mr. Microscope]

IDK the "should", but I do about every three weeks when I replace my GFO.

 

Good question for basic review. Following.

[Mojado]

I'm at about 50 days on my carbon, 70 days on my Purigen.

[Mr. Microscope]

I'd say you're a bit overdue, but maybe I'm wasting my money changing too often. I will say I notice more clarity after I change mine each time.

[Mojado]

The old posts I found said once every 90 days.

 

My Kent Marine Reef Carbon jug says "For best results, replace carbon monthly in freshwater aquariums and use intermittently in marine aquariums". This sentence blows. It addresses both freshwater AND marine aquariums, but gives different types of information for each. I guess the freshwater aquarium number is a good ball park figure for marine aquariums.

 

If I wanted to ensure folks were satisfied with my product (Carbon), I'd recommend the time between change-outs based on an overstocked aquarium to ensure that my product performed as desired under the worst conditions. So . . .maybe 2 months is the worst case number. Maybe 90 days is OK for an appropriately stocked aquarium?

[wow.such.chris]

I only use activated carbon as a method of water clarification and keep it around in case of allelopathy. I use it sparingly and only as needed until I no longer notice any clarity issues which isn't long.

 

In Sprung and Delbeeks "Reef Aquarium" I recall them citing that carbon remains active for something like 6 months? At least thats what I can remember without looking it up.

[Mojado]

I only use activated carbon as a method of water clarification and keep it around in case of allelopathy. I use it sparingly and only as needed until I no longer notice any clarity issues which isn't long.

 

In Sprung and Delbeeks "Reef Aquarium" I recall them citing that carbon remains active for something like 6 months? At least thats what I can remember without looking it up.

 

So you use it sparingly, as directed basically. Hmmmm, so its use is something that is subjective?

[Polarcollision]

recently researching similar question. I thought this was a great link: http://www.theaquariumsolution.com/rowa-carbon-question

 

"In general, all carbons used in salt water have an absorption curve that peaks rapidly in the first 24 to 48 hours. Adsorption then drops off gradually over the next 10 to 14 days, partly due to the media becoming more saturated with bound organic dies and dissolved organic compounds, but also due to increasing bacterial colonisation which gradually fills the porous structure limiting further uptake. By day 14, the carbon is effectively useless.

 

The two day recommendation is based on the premise that after 2 days, the carbon isn't performing at peak levels and has done most of its work so can be removed. And that an average aquarium will happily function for several weeks between carbon usage.

 

In the USA the alternate method is to use larger quantities over longer periods, swapping it out for new media every 10-14 days maximum. This method is based on the idea that it is better to run carbon constantly rather than intermittently, to increase long term system stability and to avoid gradual increases in organic dyes etc between changes. But this isn't a method that should be initiated in one quick change as it may shock some sensitive corals if water clarity is suddenly increased allowing greater penetration of intense lighting. So the trick is to build it up slowly if you are going to use this method. What happens over time is that you get to a stage where the amount of organic dyes present in the water as well as other dissolved organic compounds are at levels low enough that they don't saturate the amount of carbon you are using so quickly, so the adsorption curve is flattened out over a longer period because the carbon isn't limited by its capacity any more, it is now limited by the 'availability' of material it can sequester from the water. But the bacterial colonisation rule still applies, so at day 14 maximum, even if the carbon isn't saturated, it will be blocked by bacterial growth so will need replacing."

[Mojado]

recently researching similar question. I thought this was a great link: http://www.theaquariumsolution.com/rowa-carbon-question

 

"In general, all carbons used in salt water have an absorption curve that peaks rapidly in the first 24 to 48 hours. Adsorption then drops off gradually over the next 10 to 14 days, partly due to the media becoming more saturated with bound organic dies and dissolved organic compounds, but also due to increasing bacterial colonisation which gradually fills the porous structure limiting further uptake. By day 14, the carbon is effectively useless.

 

The two day recommendation is based on the premise that after 2 days, the carbon isn't performing at peak levels and has done most of its work so can be removed. And that an average aquarium will happily function for several weeks between carbon usage.

 

In the USA the alternate method is to use larger quantities over longer periods, swapping it out for new media every 10-14 days maximum. This method is based on the idea that it is better to run carbon constantly rather than intermittently, to increase long term system stability and to avoid gradual increases in organic dyes etc between changes. But this isn't a method that should be initiated in one quick change as it may shock some sensitive corals if water clarity is suddenly increased allowing greater penetration of intense lighting. So the trick is to build it up slowly if you are going to use this method. What happens over time is that you get to a stage where the amount of organic dyes present in the water as well as other dissolved organic compounds are at levels low enough that they don't saturate the amount of carbon you are using so quickly, so the adsorption curve is flattened out over a longer period because the carbon isn't limited by its capacity any more, it is now limited by the 'availability' of material it can sequester from the water. But the bacterial colonisation rule still applies, so at day 14 maximum, even if the carbon isn't saturated, it will be blocked by bacterial growth so will need replacing."

 

So the carbon needs replacing every 14 days to maintain some degree of performance. If the carbon, after 14 days, is no longer doing anything, then is there no harm leaving it in until the water clarity/color dictates it needs to be changed? My Kent Marine carbon says, iirc, that it does not leech back into the water column . . .if this is true, then "leave it in until water dicates it is time to change again" seems like the best way to go. Thoughts?

[hypostatic]

i basically change mine when i notice a decrease in water quality, or notice that my corals are getting stressed due to allelopathy

[BeardedReeferLLC]

every 2-3 weeks.

[GHill762]

I change mine every other week when I remember.. sometimes it goes a month or longer..

[frag collector]

I buy my carbon in bulk, Activated coconut carbon and make my own filter bags out of old pantyhose my wife keeps around.

 

I change the carbon every month. Cheaper carbon every two weeks.

 

I rinse the bags under r/o before placing in the reef tank. And rinse the particulate that collects every week in the old water after a change.

[GHill762]

coconut carbon?

[Polarcollision]

coconut carbon?

 

I read about that somewhere... something to do with the different types of carbon and what they're made from. Here's more reading if you're interested: http://www.tigg.com/activated-carbons-different.html and http://en.wikipedia.org/wiki/Activated_carbon

[Polarcollision]

So the carbon needs replacing every 14 days to maintain some degree of performance. If the carbon, after 14 days, is no longer doing anything, then is there no harm leaving it in until the water clarity/color dictates it needs to be changed? My Kent Marine carbon says, iirc, that it does not leech back into the water column . . .if this is true, then "leave it in until water dicates it is time to change again" seems like the best way to go. Thoughts?

 

I had been changing my carbon out once a month in my 8 gallon. It would have the bacteria biofilm covering it when it was replaced. My best guess is that it was doing what the live rock and sand does: growing bacteria that process nutrients/and some of the nitrogen cycle. Changing it out every month likely prevented too much build-up, and then the new carbon cleaned up the water until exhausted.

[blown 346]

I dont use carbon like stated unless there is a water clarity issue. Carbon will remove essential elements in the water that the tank needs, as anything you dose will be affected. So its pointless to run it in a reef setting

[Polarcollision]

I dont use carbon like stated unless there is a water clarity issue. Carbon will remove essential elements in the water that the tank needs, as anything you dose will be affected. So its pointless to run it in a reef setting

 

I noticed this when using chemipure. I always had to add magnesium. When I switched to just activated carbon, mag stopped dropping and i no loner have to dose it. Never checked anything other than NO3, Alk, Ca, Mg, PO4, so I'm curious what other elements you saw dropping?

[hypostatic]

activated carbon is known to absorb iodine

[Polarcollision]

activated carbon is known to absorb iodine

 

I just became convinced to put carbon in for 48 hrs, then take it out. No wonder my iodine levels were always low when I tested.

[hypostatic]

Well I actually leave mine in all the time haha. My tank's water is pretty heavily loaded with stuff, so i guess the carbon gets exhausted before it can really absorb too much iodine in my system

[mickeymouse]

I change mine when water quality seem to have dropped.. but i would say once a month or so... maybe every 5 weeks..

[(oYo)]

2 weeks

[frags]

Like said previous it is not worth having carbon in your tank after 24 hrs. Gfo on the otherhand will last longer.

[Mojado]

I summarized these posts in my post 1.