Carbo-Plus CO2 system. safe?

[Phish-head]

Looking into the Carbo-Plus CO2 system. Looking for any feed back as far as how it works, safety, etc. Its basically a carbon bar charged with a certain amount of voltage that can be regulated. Very nice, neat little unit. Says its safe (only gives off 7 volts?) My concern is the electrical current it gives off. If tank is properly grounded, should I even be concerned?
Thanks in advance

[OrionGirl]

I run one in my 55, and have never had a problem with it. I have it on the lowest setting, and it has really perked up my plants. The fish treat it like just another hiding place.