I have an fairly well established 40 gal Oceanic tank lit by their standard spectrum twin flourescent tubes planted with Java Fern, Dwarf hairgrass, Water Sprite, Amazon Sword and Cabomba. I'm using Flourish and Red Sea Flora Fe as supplements. My Flora Fe iron test kit never reads iron even if it is present - not sure if I got a bum kit or what. Anyway, the water is fairly soft GH 3, KH 4, PH 6.9, temp 78 and is filtered by Fluval 305 canister. Substrate is medium sized natural round gravel and the tank gets about 12 hours of light per day. Both the Amazon Sword and the Hair Grass are potted. The grass has steadily thinned and died off, the amazoon has lost some of it's vitality as well and the Cabomba seems to grow in spurts (I trim it and replant in bunches) then falls apart where planted at the gravel. The Water Sprite and Java Ferm are the the only ones that look close to as good as when originally planted. I'm trying to save the grass and restore the other plants to their original vitality. Are these supplements enough or do I need CO2? I was considering the liquid CO2 from Natural Aquarium Vital instead of installing a generator. Lastly I need to be safe with the additives as the tank is stocked with fish - tetra's, barbs, cory cat, algae eater and a few snails (that hitchhiked on one of the plants) - Angels or Discus will be introduced soon. Thanks for any advice.