Question regarding De-chlorinating Water

The Madd Hatter wrote in
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Hiya Folks!

I've been away from the group for a while, since my sis was getting
married, but now she's hitched and gone!

I have a question regarding chlorine content in water... I've always
used some form of dechlorinator or the other, but I ranout the other
day, and a fellow hobbyist told me he doesn't use any at all. He does
20% to 50% water changes, w/ regular tap water. He did say his tanks
are VERY well aerated though... Is it neccessary to add dechlor to the
water if you're doing small changes like 10% to 20%? Doesn't the
chlorine evaporate fairly quicky if you have good movement inthe water
column?

I'm going to be getting a couple of barrels to hold water for my pond
(for the water changes), since we're talking a lot of water, but can I
get away w/ filling my tanks straight from the tap?

BTW, all my tanks have Rift Lake Cichlids... Setups vary from large to
small, w/ all different types of filtration....


When I was just starting out in fish keeping, (this was over 20 years
ago), I had a single Tanganyikan tank and would do 25% water changes
without adding dechlorinator. Never noticed any problems. Then, one day
I decided to do a 75% water change. My Julidichromis started going into
convulsions immediately. All the other fish died soon thereafter except
for a single leleupi, but it suffered some sort of permanent gill damage
(the gills turned a permanent bright red color).

So I guess the lesson is that you can get away with doing small water
changes without dechlorinator, but you are taking big chances. Moreover,
even small water changes probably needlessly stress the fish and might
harm the biological filter. The extent of the risk may vary from
locality to locality however. In some locations, chloramine in addition
to chlorine is present. Chloramine is highly toxic to fish, whereas
chlorine is only mildly toxic.

Meph