"JB" wrote in news:1169100638.503928.99030@
38g2000cwa.googlegroups.com:

I ahve the standard Whipser HOB filter and have been using the filters
with carbon.. I recently discovered a site that said you should remove
the carbon to keep beneficial bacteria going through the filter...

Is this true?


Nope. Carbon doesn't affect bacteria at all. The beneficial bacteria
all sticks to whatever surface it can find, they aren't water-borne, so
the idea of removing carbon to keep bacteria going through the filer is
misleading.

There are only limited circumstances when carbon filtration is useful,
and unless you have a consistent source of supply for it, it has widely
variable effectiveness and rates of depletion.

Carbon is good for;

1) removing copper-based medicines from the water stream, once treatment
is concluded

2) reducing tannin-based water discoloration ("tea water") in planted
tanks

3) removing some heavy metal contaminants (lead, antimony, a few others,
but not mercury)

4) removing dissolved organic compounds, to a lesser extent.


THe problem with that last (which is I'd guess the reason why filter
makers always include it) is that few hobbyists have a means of
measuring d.o.c., and thus have no clue when the carbon stops working.
Add on to that the issue with variation in rates of depletion, and you
can see why so many people are skeptical of its efficacy.

Personally, I have a consistent source of local supply for bone
charcoal, which I use to treat a 20g planted tank with a history of
discoloring. I replace 1/2 cup monthly in my filter, and my water stays
low in color. If I stop, the color comes back. I'd use the smae
charcoal if I ever had to clean tank water after an ich treatment.
Other tanks do just fine without carbon in the filter. You might want
to replace the carbon's surface area with something else to grow
bacteria on, though, or you might lose a little bit of your tank's
capacity to handle ammonia/nitrites.

DaveZ
Atom Weaver