I use my Fluval cannisters as diffusers in all my tanks now, one 305 at 4 to 5 bubbles per second. It's been over a year and I've not had any problems. While this method does work well, I'm pretty sure an inline diffuser would probably be more efficient. The cannister does occasionally burp out a burst of C02 bubbles which is a waste. Its just to easy to use the cannisters and I'm to lazy to get and install an inline reactor!
90 gallon, Crypt undulata "broad leaf" Lobelia cardinalis small and large form. H.corymbosa "compact" Crypt parva, Crypt Red Wendetti Downoi, Bacopa, Samolus Valerandi, Limnophilla Aromatica Alternanthera Reineckii lilacina(purple)
2x 150 Wt 10000k HQI Metal Halide, 2x 65 Wt 6700k-Colourmax