You are worried about the water refilling the tank straight from the tap,
chlorinated....all you need to do is put the dechlor in the tank before you
switch it to fill.
It's not going to harm your fish (adding it first).
When you can do water changes on a few tanks in 15 mintues and not use
*one*
bucket.....water changes become a weekly breeze!

Boy, that sure would save a lot of work. But I'm still skeptical. Are you
doing it that way? No adverse effects to the fish? I'm a newbie and
everything I've read has advised to treat water before you add it, and some
even add that you should aerate it and age it first! Thanks, Cheryl

15 - 20% water changes straight from the tap (temperature close
to tank temperature, of course) will not harm fish.. No dechlor
necessary. Over that, you should use the dechlor.
If you want to be sure, there are cheap test strips for
chlorine/chloromine
that you can use.

Many of us have enough tanks and experience to confirm.

bob