I use a low tech CO2 injecter in my tank with the "Ladder" in the back. I got 'er at Petsmart, but make my own concoction of yeast and kitchen sugar with warm water for the "refills," if you will. It does well. It starts out slow, then I get a bunch of bubbles, then it slows down again.
I have this at the back of the tank, between the filter and the thermometer. I have an oxygen bubblemaker thing, but I don't run it nearly as fast as it comes out. Just a bubble every now and then.
You can kind of see it a little in the back. This is right after trimming, it's normally much more filled in. :}