“Wont simply boiling the water you are adding to the primary remove the chlorine?” Boiling will indeed remove chlorine. I am not a utility water expert but I think the majority of public water is using chloramine these days (since chloramine is more stable than chlorine). So, if the OP contacts his public water provider and finds out that his tap water contains chlorine then he has the option of the boiling method. He will need to boil his ‘top off’ water and let it cool down prior to adding it to the primary. A ‘benefit’ of the carbon block filtering method is that in addition to removing chlorine/chloramine it will also remove other aesthetic volatiles (if they are present). Cheers!