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