Your chlorine loss should be negligible, not massive. I think you have a fight on your hands (with something that is using up your chlorine.)

Remember: You want the chlorine there to kill dangerous contaminants. Not to be too disgusting but every person who gets in your pool brings a very,very, very small amount of fecal matter--and the chlorine rapidly neutralizes that and renders it safe, sanitary and harmless. If algae is using up your chlorine you lose that protection.

That should reassure you that doing this is the right thing.