Here's something I've always wondered, but never really pursued an answer. What are the ramifications of overdosing CO2? I know that fish and shrimp et al can die, but what are the limits regarding plants? Is it a ph issue? I know the reccomended amount of CO2 is 30ppm, why? How far away is this to saturation? If this has been covered in the past, does anyone have a link to the thread? I'm too lazy to go and blindly look.