Red Wall, Wow that nice. I guess all I would need is the tank (what size?), a bubble counter, tubing, and diffuser?
For the paintball tank, you should get the biggest you can, a 20oz, which are large. Just go to any outdoors store/walmart and find the biggest paintball co2 tank you can find.
You may not need a bubble counter depending on what diffuser you have, some have a built in bubble counter. Other than that, you are fine - if you want to play it really safe, you can pick up a cheap check valve.
(here's a link to one that is a 3 in one! http://www.kensfish.com/product3820.html
BTW How many bubbles per minute should I use if I have an 8hr light duration in a 6 gallon tank. Im mainly just worried about hurting the fish.
I'm not sure, as I haven't run co2 in a tank like yours, but you should also get a co2 indicator http://www.kensfish.com/product3790.html
I was looking at this route at first as well, but there have apparently been stories of people's check valves shooting off. The valve that is linked here does not regulate the INITIAL pressure. There is about 800 PSI coming out of the paintball tank, the regulator that I linked to regulates
the initial pressure coming out of the tank, lowering it to a workable pressure, I'm fairly sure you can control how much. Most needle valves are rated for only 400 psi. The valve that pinoyboy linked to only opens the paintball cylinder, the needle valve (rated for 400 psi) controls the flow from the 800 psi cylinder.
I believe this is the main reason that some people have troubles controlling the bubbles. It could work and you may never have some problems, but I know that the general consensus is to spend a bit more to get results that you may very well end up paying for in addition to the cheap thing you get.