Well I'm unsure about co2 now (even tho I've just got a pro set)
I've just seen tank in a garden centre that looked stunning, very green and very healthy plants. Every leaf on the 4 java ferns had little baby ferns on then, I was gob smacked.
I asked the fish guy about it, saying it must have co2 in there, he said no, all we use is easy carbo every day. Wow I'll be using it on my edge from now on.
Ps got s bottle from them as it was half price, sorry Johnny