I just bought some nutra fin dechloranator and I have a question about how much to use. On the back it says to use 5ml per 10 gallons to remove chlorine and to use 10ml per 10 gallon to remove chloramine. My water has chloramine (I think) so do I really have to use 10ml per 10 gallon or are they just trying to trick you into using more dechlorinator so you run out faster and have to buy their product more?

I calculated this would last me 66 years with the current tanks that I have.