"chatnoir" wrote in message
ups.com...
On Jul 10, 2:32 pm, ~ jan wrote:
On Tue, 10 Jul 2007 09:28:08 CST, Derek Broughton
wrote:

The problem with chlorine and organics is that the combination produces
trihalomethanes (THM) - which are pretty bad for people. Does anybody
know
what they do to fish? (Apparently somebody does - the EPA has a report
about the effects on Striped Bass at
http://oaspub.epa.gov/eims/eimsapi.d...?deid=40377but I don't want
to spend $17.50 to get it only to find it doesn't mean anything to me -
I
wasn't even sure about the term "Hepatocyte").

In drinking water systems, the aim is to filter practically all the
organics
out of the water before treating with chlorine, to keep the THM levels
within EPA limits. If the THMs are a problem with fish, you really
don't
want to use an organic filter to remove chlorine. [damn, I met an
expert
in this sort of stuff two weeks ago - but did I know then I needed to
get
his email address?]

Hmmm, sounds like dechlor all the time might be wise when using tap
water?
Usually for a top off we usually say don't worry, but the chlorine is
surely reacting to the organics in a pond system, thus creating this THM?
~ jan
------------
Zone 7a, SE Washington State
Ponds:www.jjspond.us

What about this?:

http://tinyurl.com/2bn7a5

That type of filter should be listed for a certain number of gallons, rather
than a minimum time. It is a charcoal filter and when it is full, it is
full. The use for an aquarium for a year would be different than for a
10000 gallon pond. I have seen koi killed using a carbon filter that ran
out of steam. If you are going to use one of these, it would be a good idea
to have a chlorine test kit for a swimming pool to check the charcoal filter
to be sure that it is still working.