^ Yep, you would probably need root tabs.
Here's a DIY method for a CO2 injector:
1.) Get a 2 liter soda bottle, fill with sugar water, toss in some yeast(bread, beer and wine all work just dandy).
2.) Drill a hole in the cap and hot-glue an air tube into it, and run the tube into the bottom of your aquarium.
The yeast will go on producing CO2 for weeks at a time. If the sugar water stops bubbling or the water goes green, unscrew the cap, toss the bottle, and start with a fresh 2-liter. If the soda is cheap enough, you can add the yeast straight to it!
^ sorry, I forget what the exact source is but I got that from a planted tank forum