[Sir_BlackhOle]

What kind of test do you use? It should tell you if that measurement is ppm or degrees of hardness. Also, if you are using well water and a water softener you may not have enough hardness. Planted tanks arent really as complicated as it may seem from reading everything you see online. Once you figure out what you need to do for your particular setup you should be fine, and thats what we're here for You test kit booklet should give you some kind of info on how it measures hardness.

 

[Sir_BlackhOle]

Try a local welding supplier or home brewing company for a co2 tank, regulator, and needle valve. Some places will rent the tank to you. For a cheaper option you might use Carlos' DIY suggestion. A couple 2 liter bottles, sugar, yeast, airline tubing and your set.

 

[Sir_BlackhOle]

That looks like it would work. You attach just regular airline tubing or silicone tubing to the needle valve. These can be found at your LFS. I would go with silicone because it will last longer compared to the regular airline tubing. This goes either into some sort of diffuser or into the intake of your filter. The filter impeller will chop up the bubbles and mix them with the water. I use an ehiem diffuser i got from drsfostersmith.com that works very well.