@tom: as muji said, providing your current parameters will help alot.
what water are you useing to add back to the tank? if its RO water, are you adding minerals back to it?
what shrimps do you keep?
@lillith112: chlorine will evaporate out of the water you are correct, but chloramines wont these can be dangerous i belive.
@Muji: wow, i feel lucky, my tap water is almost perfect for CRS. the ph is a little high, 7.1 , but the GH is 3.5 and kh 1
and i use a hma filter.