[danny zubot]

This is a really interesting topic.
Has anyone put your hand in your tank after having a smoke? Did you see the reaction of your corals? Remember that an aquarium is in one form or another a big lung that is always absorbing O2, skimmer or no skimmer. We all know that second hand smoke contains elevated levels of CO2 and CO which are absorbed by othe lungs and definatley aquariums. Elevated CO2 will cause your Ph to drop overtime, though I'm not sure how long.

There's not much you can do about protecting the surface of the water against toxins short of sealing the tank and venting it outside. But as far as skimmers go, build a carbon bong for the air intake and that should help.