Discussion in '3reef Site Polls' started by Matt Rogers, Jun 22, 2005.
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Curious how often you change your carbon... looks like I am on a 4 week cycle.
well i used to change it even 3-4 weeks but now i dont use it anymore...i look out my filter lol
hey matt why r u sad?
I like smaller amounts changed more frequently because once a biofilm builds up on it, Carbon become useless. At that point, the bacteria will start re-releasing P. However, that is NOT when GAC releases most of it's Phosphates. It's when it's brand new that this occurs. That's why I soak my Carbon in RO/DI water for 24 hours before using it.
I am on the 3-4 week cycle as well. Interesting idea about soaking in the RO/DI water. I have never heard/thought of doing that.
WOw.. that is interesting. Got a link Curtis?
I use Purigen, it seems much more effective at removing, plus it can be regenerated
Yes...I have lots of info on the subject. Gotta run for several hours first though.
I have seen a lot of things on the internet boards that leads me to believe that people think that carbon adsorbs Phosphate and then later re-releases it. This isn't true. The carbon came with the Phosphate already in it. (Remember that ANYTHING alive has phosporus in it....Carbon was once a tree that was living....hence the Phosphorus). Luckily, most Carbon's are acid washed now so it's not as big a deal as it used to be.
The time that the carbon releases the most Phosphates is when it's brand new. Soaking it in RO/DI water will remove most of the Phosphates fairly quickly if it's a good brand of Carbon. Even Leo Morin, the head chemist for Seachem recommends doing this. http://www.hallman.org/filter/carbon.html
Most carbon sold for hobbiests has gone up in quality in recent years but there is still a difference in effectiveness. See these links
Activated carbon is used in the food industry, chemical industry, etc. because there is a method of things getting inside small pores.
Viscous Entrainment occurs naturally with both GAC and Live Rock. We like the more porous live rock because of it's increased potential for biofiltration. We like the more porous GAC because of it's increased potential for filtering as well. I don't want to get too complicated here because fluid dynamics are difficult even for scientists. Here's the basics on how carbon works. A single pound of activated carbon has the surface area equal to 125 acres. Very porous stuff. It has been baked in such a manner as to create all of the different types of pores and surface area. Quotes are from Calgon who supplies much of the Carbon sold in America. http://www.calgoncarbon.com/resources/faqs.cfm#one
Basically the bigger holes.
Basically the smaller holes.
Basically, this is how Phosphates are adsorbed onto LR (and into LR). Van der Waals forces are exactly how a protein skimmer works as well.
http://www.chemguide.co.uk/atoms/bonding/vdw.html (Van der Waal forces)
Ok....if you're not sufficiently bored yet, here's the bio-film explanation.
If you add a piece of LR to your tank, the bacterial population will expand and cover every surface of that LR. If it is porous LR, the bacteria will even grow on the inside. They create an invisible, to the naked eye, film called biofilm. For those so inclined, here's your link. http://www.erc.montana.edu/CBEssentials-SW/bf-basics-99/bbasics-01.htm
A bacterium really isn't a picky critter. It just wants a house and it wants to eat. It doesn't take too long for them to find a house AND food in your Carbon. They will create a biofilm covering the adsorption pore spaces rendering them useless in a very short period of time. (One to two week max.)
If you leave the Carbon in longer, what's going to happen? Nothing good IMO. The Carbon is covered by a biofilm so it is no longer doing its job at adsorption. Bacteria are thrilled to death that they have a food source. Unfortunately, the life span of most bacteria is measured in hours and not years. They will eat the nasties that were chemically bonded to the Carbon and then die, thereby re-releasing that nasty (including Phosphorus).
That's why I use smaller amounts of Carbon, soak it in RO/DI water, and change it out often.
Oh my God. This has to be the motherload of carbon posts. Thanks a lot inwall for your effort!!!
I looked at a couple links so far. I will look at them all soon. Great stuff. Looks like I need to upgrade my carbon at the very least. Ultimately I hope I grasp all the views here so I have better techniques and practice in husbandry as well.
How often are you changing it out? How much are you using? How many gallons is your setup?
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