Can you have too much co2?
I just started a DIY co2 system for my 2.5gal nano and it's really kicking ass now. It's run through an air stone and I have it placed under the intake of my filter. Some must be sucked in, but it's a sponge filter (sort of...) so not all is making it in. I have a constant stream of very small bubbles running slowly to the top of the tank. most are breaking on the surface right now.
Can you have too much co2 in a planted tank? I know too much will kill animals, but can it be bad for the plants? Will it considerably lower the pH? I ask because I'm thinking of putting it into my spray bar (it's totally submerged) so I lose less co2 into the air.