Hello; I gather you put the tap water directly into the tank without any waiting peroid??
While I do not use dechlorinaters in my change water, I do allow it to sit in containers for a few days first. Usually at least four days, often more. I also have bubblers in my larger storage bottles. This has worked for me as my water company only uses chlorine to treat the water. If chloramines are used, this method is not supposed to work.
To your question. My initial take is that there is not likely to be a completly safe amount of chlorine treated water to put directly into a tank. This is a guess only and not from experience. I do not know how much can be added before problems show up.
I recently took part in a thread about a tank crisis. One possible explaination for the death and damage to fish was chlorine in the change water having killed off the beneficial bacteria (bb). It was speculated that the dechlor stuff was old or too dilute to bind up the chlorine and chloramine. Once the bb were gone, then ammonia could build up to toxic levels. I am still not sure this was the only problem, but seemed a decent working theory.
When I set up a new tank and fill it with tap water, I run it empty, no fish, for a few days with some sort of filtration or bubblers going. I then put some live plants and snails in for a few days.
I will follow this thread to see the other responses. Keep in mind that we fish keepers often have a wide variety of opinions on just about every issue. Expect conflicting answers. How you choose which to go by might be dificult.
Good luck
