By the way... I have a beautiful 72 gallon fishtank, fully planted with live plants, and a 20 lb tank of CO2 in my bedroom that slow bleeds bubbles into it to keep them healthy. Yeah, I said it CARBON DIOXIDE!!! In my bedroom, in a 20 lb industrial tank I purchase only a few blocks from here... So don't tell me I don't know the truth... CO2 is NOT pollution... it's plant food!
I used to have a 55 gallon salt water tank, long time ago. I never though to induce CO2 to help the plants grow - good idea.
My prize was my lionfish. After a couple years he had grown to nearly 10 inches nose to tail, and ate 6-8 feeder goldfish a day. Then I joined the Navy and had to give the tank away to a neighbor. I was a bit careless when I was transferring him, and I got stung on my thumb. Nasty thing, lionfish stings. They have a venom similar to that of a cobra (I later found out). My thumb swelled to twice its normal size in a few minutes, and felt like it was being pounded by a hammer. My first thought was to get the poison less localized (and diluted, so perhaps my system could deal with it), so I put my thumb under very hot water to dilate the veins. It helped. The swelling wend down some and the pain lessened.
Later that day I went to visit my brother. I told him what happened, and he called our mother! Between them both, I was forced to call the poison control center (they actually wanted me to go to the hospital, but I hate doctors). Funny thing, when I talked to the Alameda poison center (one of the best in the nation) they had no idea what to do. They had to call around, and finally down to San Diego, to get any information on lionfish venom.
After a couple hours of phone calls with them they told me, there is no anti-venom, but... apply heat - as much as you can stand. It neutralizes the poison.
Turned out, my initial instinct was correct - but for the wrong reason.
I went through all of that for two reasons.
First, now you know what to do if you are ever stung by a lionfish.
Second, while CO2 may be good for plants - it is not so good for such things as shell fish. It weakens the shells. It may be bad for coral, as well.
Everything needs to stay in the proper balance and proportion, or something is going to suffer.
So while your initial instinct to help the plants is correct, it is also wrong reasoning when it comes to the overall health of the entire ecosystem. (Just as my instinct to apply heat would have been wrong if the poison had not been neutralized. I could have just as easily died by spreading the poison to my heart.)