I recently decided that it would be best to start gradually planting my tank, looking towards having it heavily planted in the future. I feel that my fish might enjoy a planted tank, and it is also quite pleasing to look at. So I was going to start with some dwarf baby tears to spread along the base of my tank, but I heard yo grow them you need a CO2 cartridge. I really do want more plants in my tank, but is a cartridge really necessary? I thought that the byproduct CO2 from the nitrogen cycle would be enough, that and the byproduct of respiration, but I have been browsing and in most cases, I have heard CO2 cartridges are a must. The reason, although I am so opposed to it is the many "CO2 fish death" posts and pictures around the internet. I am scared all of my fish will die as a result of the cartridge. The main cause of death, I have seen on many forums, is a sudden decrease in ph. Now I think the Co2 might actually be okay, because my tank normally has a ph of 7.7. A lowering wouldn't be a problem, right? So, will the CO2 cartridges kill my fish, or can I just get by with no cartridge for a planted tank? Also, my tank is using a gravel substrate, so the fish waste does add plenty of fertilizer, i don't know if this will compensate for anything, though.....