I dont know what one to get. The tank is a 30 gallon and i will be setting it up soon so quick answers appreciated. I would like to buy a kit of some sort so i can get all of the peices needed to keep my aquarium plants healthy.
Cheapest and easiest way in the long run is to get a CO2 tank and regulator. Once you pay for the tank and regulator, CO2 is pretty cheap and lasts a long time.
I took off my CO2 tank when it ran out and I am just using Flourish Excel, and for me it is working just fine. The Excel is like $40 a jug, so it is more expensive, but well worth it.