Carbon in aquaria and human consumption 6/12/06 Greetings Crew, <Hello> I have been reading through past posts about the use of carbon in marine and freshwater systems and have a question. <ok> In answering questions on carbon and how long it lasts, more than one crew member responded that carbons' usefulness lasts only a few hours to a day or two at most. <Yep> It is suggested that after this period it is no longer 'activated' so to speak.  I know that Brita and other manufactures use carbon for their water filters.  They also allow for 30 days or so of usage before replacing.  Does this mean that their filters aren't actually doing anything for 29 of those 30 days?   Thanks for any help in clearing this up...no pun intended)  : ) Eric B. <Some of it is marketing, who would buy a filter that needs to be replaced every day, and some is the environment.  Tap water is going to have a lot less "stuff" in it to remove than the water from your average fish tank.  The city water system sees to that.  Also the amount of water running through a "Brita" like filter adds up to at most probably 10 gallons a day, while a filter on a normal powerfilter could push through 10X that in one hour.  Carbon basically has only so many holes in it to fill up with unwanted material.  The rate which these holes fill up depends on the concentration of impurities in the water and how much contact time with the water it has.> <Chris>

Tap Water FAQ (more on chloramine concern) Here's another tidbit of info I found:  Nice to know if you are planning on using a new filter anyways: "Advantages of running carbon include removal of unwanted colors (usually yellow), unwanted odors, and removal of other miscellaneous organic waste products. Carbon also removes chloramine (overnight), but only when the carbon is new (less than 48 hours old). Still, this can be an advantage if your tapwater contains chloramine." <I've added quotation marks... and would like to add a note to you re "testing". There are (relatively) simple colorimetric assays (test kits) for chloramine. I suggest you get and use one to satisfy your curiosity re the issues of dissipation through time and carbon removal. No need/use in being confused, unclear here. Prove to yourself what works, does not. Bob Fenner>

Re: Tap Water FAQ Here's another good resource, it turns out the activated charcoal approach leaves ammonia in the water. http://www.csd.net/~cgadd/aqua/art_chlorine.htm <Thank you for this. Will post. Bob Fenner>

Carbon Hi there, I have two questions for you: 1. Can I use carbon to break up the bond between chlorine and ammonia rather then using conditioners (de-chlor)? <Yes> And how long should I wait, 24 hour? <Should be sufficient.> 2. My brother asked me a silly question, do fishes know their owner (I think he meant the person who feeds them)? <Fish can definitely learn who feeds them and respond by coming to the top of the tank. -Steven Pro>