When I was a kid I had a friend who use to buy gold fish he had a really nice filter system and everything that should make his fish happy. His fish never lived passed a week he must have killed 40 gold fish before he found out it was the city tap water that killed the fish .
There use to be a post at the gw pond fourm but its not there anymore because its to old. The post went into detail of what tap water will do to your pond fish if you dont treat it first .
I use stress coat to treat the water it takes care of the Chlorine . Iv never seen anything that just removes Chlorine made for fish .
Chlorine not only affects the gills of the fish but it also kills the nitrifying bacteria in the biofilter. The resultant spikes of ammonia and nitrite together with the initial damage done to the fish results in the death of the fish 3-5 days after introducing chlorine into the system.
Any pet store that sells freshwater tropical fish probably also stocks a commerciallyprepared compound that contains sodium thiosulfate, which safely inactivates chlorine by a chemical reaction that results in formation of sodium chloride (salt).
And I agree 100% with drosera on the filter. A filter is a good thing to have yes you dont need it but the fish will live a much longer and happyer life with one .