Large Vol. CO2

  Hi, I am a new user of this list and have a question.

  My test kit reveals that I have NO free CO2 in my tanks for the plants.
 Ph=7.6 and hardness is very high ( I think past readings have been 17-30
degrees of hardness)  I have many tanks with non plant eating killies..small
2-10 gallon tanks and a few large tanks up to 240 gallons.

  I am considering a high volumne CO2 injection system into my standard air
system using a CO2 compressed gas cylinder bleeding into the air system to my
60 or so tanks.

  1.)   Is this feasible?
  2.)  Is there any  danger to human health by bubbling CO2 into the rooms of
my house?

  Comments Appreciated.

        Thx....Richard Bennett (rbennett01 at aol_com)