This critical component of the planted tank often gets overlooked, so let's talk about it What are you using and why? More importantly, where did you buy it? I have tried the following methods: - ceramic diffuser into wavemaker (works ok, but lots of equipment in tank. requires regular cleaning) - CO2 line directly into filter input (worked really well, but risks damage to the filter) - Inline ceramic diffuser on the filter output line (Up Aqua). Worked well for about 6 months and then not so much, busy cleaning it now. All parts mentioned were purchased from ebay. I have not gone the reactor route because I have been unable to source parts for it. The inline diffuser seems to be a winner, but cleaning it is a pain.