Interesting read for more info on Activated Carbon if anyone cares to read more about it.
I agree that carbon shouldn't be left in the filter full-time, nor should it be left after doing a treatment to remove meds from the tank, but my thinking is because it is pointless to have it there more than because the carbon itself will cause a problem.
Are you saying that carbon shouldn't be used to remove meds from the tank, or just that it shouldn't be left in the tank after removing the meds, say after 24 hours or so?
Hes probably read a thread about carbon causing HITH if hes concerned about what carbon "might" cause. (random guess because there isnt much else to worry about, correct me if im wrong though) There are quite a few big discussions out there which i read a few years ago myself.
I tend to not bother with carbon, but i do keep some in case i want to "de-med" my tank any time in the future. It is supposed to aid bio filtration, but its not used as a primary source for bio bacteria, purely because it takes up valuable space which could be used for bio sponges/ceramics which bacteria are supposed to establish themselves on more easily. Plus those people with small filters cant afford to sacrifice much space for it.
My link above it quite useful for info on carbon if you want to read some more into it
I'm not saying that the carbon is a bad thing, just an unnecessary one the vast majority of the time. It is best used to "de-med" as you said. Beyond that, there is no
need for carbon. Other things can do everything else that carbon is supposed to do. Carbon isn't a bad thing, but it is expensive to buy and if you replaced it every time it was "used up" you would be replacing it constantly and that can run into serious money.
The biggest thing that many folks falsely believe about carbon is that it can "de-adsorb". (Please note that there is a big difference between aBsorbtion and aDsorbtion.) Carbon will not "de-adsorb" the things that it has adsorbed back into the tank. Phosphates
can be leached back by
some carbon, but phosphates are not bad things in their own right in a freshwater tank (which is where this thread is, so I assume this discussion is purely regarding freshwater aquaria). And can easily be controlled by proper maintenance water changes. Again, contrary to belief by some, phosphates do NOT cause algae. However, excess phosphates can accelerate algal growth, but the cause is from other sources, primarily ammonia, CO2 and light.
The only reason that I suggest that you remove carbon after removing meds after 24 hours is that it really serves no purpose that can't be handled by other means. As Tizer stated (and I am not disagreeing with the vast majority of your previous posts Tizer, just the comment about it leaching "nasties" back into the tank), the space devoted to carbon can be more efficiently used by other media. I will mention though, that currently I have a carbon cartridge in my tank, because I haven't bought the replacement media that does not contain carbon. Marineland sent me a free box of replacement cartridges for my filters as part of a return/exchange with them. I've left the carbon in place now for over two months, and I feel no need to make any changes to my filtration set-up because I don't
need to use any extra media (I've already got two filters, one with carbon, one without, plus some ceramics and an old sponge that I used to cycle my set-up). The carbon is part of the filter cartridge and would be far too much trouble to remove than it is worth. However, once I purchase the non-carbon replacements (in about 6 months or so), I will keep the carbon cartridges around as needed for med removal. There is no danger though that the carbon is leaching anything back to the tank.
